Hi Choccy,
Concurrent planning and a standard adoption are very different things in amny ways
Standard - child is taken into FC, with a plan of going home. As the months tick by, it becomes obvious that isn't going to happen so the plan changes to adoption, and the LA will go to court for a placement order. Once a child has a placement order with an adoption plan (this allows an adoption agency to send the child to live with adoptive parents) then adoption is the only plan, and going back to the birth parents isn't in the equation at all. If you did a standard adoption then you would be bringing home a child who will be adopted by you. It is as certain as you'll ever get. Theoretically, the birth parents can ask permission to appeal the adoption, but no one has ever succeeded doing that, so unless you disrupt it yourself, the child you bring home is your child from the moment you meet them
On the other hand, with concurrent care, adoption is not the plan at first. When the baby is taken into care and sent to live with concurrent carer, the plan is to send the baby home, BUT because of the parent's circumstances, that is considered quite unlikely to happen, and so the back up plan (from the off) is adoption by the concurrent carers if going home fails. Hopefully the agency should be carefully selecting which babies are the most likely to need adoption, but that's not any guaruntee. Rarely, some parents can pull off quite amazing lifestyle changes considering what it was like before the child came into care. So yes, a different mindset is required. You are a foster carer, and will only adopt if going home fails. This is very unlike a standard adoption, as I said above. Over months, the plan will change to solely either going home or adoption. If adoption, the agency will get a placement order and from there the process goes mostly like a standard adoption, except the baby is already with you
I have seen various stats for adoption vs. going back, and I think it's around 10-15% return to the parents, but it will vary. But if you are one of the ones whe return a baby, the statistics don't matter, so you do have to be prepared for that as a possibility from the off
To the best of my knowledge, no one will stop you doing concurrent care if you have a BC. After all, many many foster carers have their own children as well! It is for you to decide whether your BC can handle the possible return of baby. If you think it's too much risk for her, then do a standard adoption, so she will only meet her definite brother or sister not just a potential one
Also consider this - with concurrent care you have to be prepared to do things only a foster carer would do, for instance handling frequent contact with the parents. In a standard adoption, you wll probably be writing one or two letters a year, and/or one or two visits a year especially with siblings, more rarely with the birth parents. On the other hand, as a concurrent carer, baby will probably be starting with at least weekly contact, but I heard one set of carers who started with 5x a week contact. This would be reduced and then stopped if adoption becomes the sole plan, but that would take months probably
You might get an even younger child with concurrent care, but it is entirely possible to adopt a child aged about 8 months-2 years without doing concurrent care, so if age of the child is influencing your decision, bear that in mind
That is very long (sorry!!), and there are adoptive parents on this board who actually did concurrent care (I didn't) who could give you great advice about the reality, but I hope that helps a bit