I think with a goodbye contact, it depends on the age of the child. If the child is very young and won't remember consciously, I can imagine that knowing later on in life knowing that you were all in the same room, that you were involved with them in a painful part of their life but helped them through it, might be helpful. It might also help BF to come to terms with you and see you not as a boogeyman, which may pay dividends later on if your child seeks them out- you are neither a saint nor an evil person, you are someone they have met and known and felt reassured by. You as adults both have a realistic picture of each other. I would be asking what harm it could do for a supervised final contact visit with a baby with someone who is essentially a stranger versus the benefits of knowing you met them later on in life. However, if the child has the capacity to explicitly remember, say is older than 2 and a half, 3, my answer might be different... although also maybe not. Although it might be a bit distressing, it can provide real closure and an outlet for grief. There is a reason we have rituals around grief and loss like funerals, and it is because it is cathartic and gives us closure and emotional release.
I try to be empathetic to BPs as well- imagine you didn't know a meeting was your final meeting with someone you loved. What would you have done differently? The regret may mean they are unable to have closure too, and who knows what impact that may have on them? Its not my place to mete out punishment. The courts have already done that by saying they don't get to be my child's parent any more, which is the worst punishment I could imagine. The idea that I wouldn't have the chance to say a proper goodbye but someone had denied me would eat me alive and make me so bitter and angry. I don't know what I would do, apart from move heaven and earth to try and find out who or what had caused me to feel such pain. As an AP, I would hate it if I had in any way caused BPs to make worse choices over something I had control over, not for their sake but for our children's. I want my kids to grow up knowing I chose empathy and kindness wherever possible because I want them to do the same. I never want them to think that I did something to hurt someone who will always be a part of them. I want them to know that I don't think their BPs are bad or dirty or shameful or evil, just people who did not have the tools and knowledge and skills to parent them in the way that I do. I can accept that part of them with grace and empathy and care, even if BPs don't have the capacity to return it and my children don't know whether they want that. Our child asks whether we are scared of BPs. I feel it would carry so much more weight if we could say of course not, we met them. To me, a final contact is so important for everyone to be able to draw a line under everything and move forward. It provides clarity to child and birth parent from someone who isn't you. It isn't you as a parent who is telling them this difficult information, which can help them to externalise and process it and then turn to you for comfort. Sometimes you need someone external to the process to deliver difficult information. The child can be angry at the professional external party (sorry SW!). And you can support and love them as their parent. As someone whose child was not told their final contact would be final, and had to tell my child myself, I can tell you that this can have lasting ramifications! It's easy for the child to feel like you are the one saying it has to be final. Allowing SWs to do that bit for you can help with their understanding and processing of that information.
I would also be assessing how it could go wrong, and balancing the risks. What does wrong look like? Is it unsafe? Or just unpleasant? Who is unsafe or uncomfortable? Is it the child or the adults? If it is the adults, can this be tolerated for the sake of the child? If it is the child, can it be tolerated for their future wellbeing? We make children do uncomfortable things all.the time for their future health and happiness. Is it possible this is one of those things?
Depending on the reality of BPs lives, it may well also be that they don't live until your child is old enough to contact them. We can't meet our children's BPs, and we know that their lifestyles are high risk. There is every chance that we may never get to meet them, and they will never meet them again. The only people who have met BPs that the children will know long term are their last foster carers. They are the only ones who can genuinely say to the children whether they act like them or look like them, and that brings up complicated feelings for me. I really really wish I could do that for them, so that I could speak about them in the way that you might do a departed grandparent- oh you have his eye, or you smile just like them. The child wouldn't have to wonder because I would know. They wouldn't have to be dependent on their FC to have that information. I know their FC are good people who wouldn't withold anything, but they don't have the same vested interest in knowing that. I can't imagine there being a part of my child's life that I wouldn't be desperate to be privy to for their sake in the future. They may never get a chance to meet them again, but imagine how powerful it would be if they knew you had. Or even if not for your child, for their children. Imagine you have a grandchild who wants to know more about their birth grandparents. I would want to be able to say I met them. You become the guardian of your child's history, not just for them but for future generations.
Alternatively, imagine your children found out you had the opportunity and chose not to take it on their behalf. You know your child best, and their history and temperament, but I know for sure my kids are so curious and insightful that they want to know as much as they can. In the same way they proclaim they don't want to eat their vegetables though, they tell me they don't want to know about BPs. And yet I find them asking me about BPs in the same way that I find them snaffling all the bloody cucumber from the fridge when they think I'm not looking. Their body knows they want it even if their head says they want haribo! I want to be able to give them as many answers as possible so they don't need to seek them elsewhere unless they actively want to.
We have grilled FC as much as we can about BPs in lieu of being allowed to meet them. How did they dress, what cars they drove, what food they ate. It informs our family traditions, we have certain food on mothers day to celebrate and honour the connection, we speak about certain professions carefully, we do certain things at Christmas and Eid to maintain a connection if the children want it. We can say we did that, but it all comes from through a FC and SW lens. Imagine how much more powerful it would be if you could know for sure yourself what they did and how they acted.
As you can probably tell, I repectfully have a different perspective to @Gruffallowhydidntyouknow and @Buttonmoon92 in regards to knowing about BPs and integrating them into our children's lives. I can acknowledge this comes woth bias though. It comes from knowing our children's BPs life history and being able to understand why they made the choices they did. The choices were definitely poor ones that were detrimental to the children and impossible to be reconciled with safe or adequate parenting, but we understand why they were made. It may not be the same in your case.
I don't really believe that you can say adopted children have a 'normal' family because they don't- they have their forever family and a birth family, and they will forever be connected, which isn't the typical experience of most children. That's OK, its nothing to be ashamed of. Normal is not necessarily aspirational! Adoption is not particularly common or normal, and we don't pretend to our kids it is, because it would be denying their complex reality. And that reality is complex and messy and we know we will have to do and commit to things for which there is no blueprint, no pathway and nobody to really guide us because the sample sizes are just too small. So few adoptions happen each year that it is impossible to really find applicable statistics to guide decisions. When you are the only person in Staffordshire to have adopted a three year old with autism in 2023, or the only gay couple to have mixed race adopted siblings in Milton Keynes in 2024, you find that its hard to rely on anyone else for exactly the right advice that pertains to your situation, and even more difficult to act "normally". Most people don't have to write a letter twice a year to BPs. Most people have never been through the adoption assessment process. Most people don't have to explain things like abuse or neglect to their kids so early on. None of that is "normal"... but it is OK. It just means you can't rely as much on typical advice.
Subsequently, the difficulty is that most advice you get is anecdotal, through adoption forums like this and adoption networks, and may or may not be applicable to your individual circumstances. It may be that you read all of the above amd know it doesn't totally apply to you- thats ok. It may be that parts of it do apply to you, but not others. To me, the process of asking for advice is about a way to guide your thinking. You can know that you have genuinely thought about each element and come to a considered conclusion based on the information you had at the time. I think that as APs, we have to just listen to other people's experiences, and make the best, most morally informed choice based on what we think to be right at the time, and extend compassion and grace to ourselves and others who are doing the same thing. It is both comforting and demoralising to appreciate that you will never be able to make the "right" decision, because there is no authority sat there judging and telling you it is black or white, right or wrong. You may never know whether it was "right". It is about making the best decision you can. That decision should be designed to both minimise harm and maximise benefit in whatever way you can, and then owning that choice you made. And part of being an adoptive parent to be is being able to sit with the complexity of your child's situation, and that your choices can affect this, acknowledge their multiple and competing realities and support them through it, and make choices with and for them that you know will either maximise benefit or minimise harm- but with the tacit understanding that you may still cause some harm or lose some benefit in the process. Minimising harm doesn't mean no harm. Maximising benefit doesn't mean totally beneficial.
Whatever decision you make, I would make it balancing and considering the knowledge that you have of BPs, of your child's current and future needs, and your capacity to get support for them and yourself to process it at each step.
I wish you wisdom in decision making- it isn't easy when it is your real life and not just some decontextualised theoretical stranger on the Internet. These are big decisions and big choices.