Yes, the Dad (who was originally just a sperm donor but did so as their friend) did see his sperm/DNA result in children and that these children were an extension of him. Maybe it was as a result of not being anonymous from the beginning but nevertheless he hadn't signed up for being a Dad but that was what happened organically. Clearly that had an impact as it was different from what was originally agreed by all 3, but really I shared it as an example of what can go wrong when the legal processes aren't followed.
As they did with the first child, the two women went through the process of the official adoption for the woman who didn't give birth, maybe they thought it was too expensive or not necessary, but then their relationship didn't work out and the lack of legal agreement and official adoption for the second child caused, or at least contributed to, a huge mess, which obviously was stressful and emotional for the adults, goodness knows who the poor kids feel.
I don't think it's as simple as the more parents there are to love the child the better. I think that's a very adult-centric approach and it's coming from the wrong starting point.
I really stress the need to seek legal advice as with this example, it was completely avoidable, they knew what was required and had organised this within the official legal framework available to them to recognise parental rights, but the second time around it was dismissed and not even initiated.
May I ask if you have a GRC yet or if that is in process? My understanding is that this certificate doesn't apply when it comes to birth certificates (and I imagine you are aware of the Freddy McConnell case and how this was rejected by the Supreme Court but is being pursued in the ECHR. Freddy is pregnant again and it is yet to be seen if Freddy will be recognised as a mother or a father on the birth certificate of either child).
This is very complex situation, even if you are mentally, emotionally and financially ready and stable, without family support, the co-parenting approach is difficult as you will need to meet someone and be on the same page with discipline, education, medication (such as vaccinations etc) on top of the legal issues and your gender dysphoria.
I think you would be best placed doing a lot of research and speaking to professionals and those who have navigated this before so to find out as much as you can. Maybe adoption and solo-parenting, with all the complexities there, would actually be easier? That's a genuine question, I really have no idea. Maybe the adoption board can help you?