Really unsure on what to do for the best here. Very traumatised by the whole thing.
A member of our family has had her child taken from her, and has been placed with an adoptive family. I don't want to give any identifying detail for obvious reasons.
I went with the birth mother to meet the adoptive parents, who were lovely. The BM feels that they are lovely, and - if her child has to be adopted, she feels they will provide a happy family to grow up in.
My issue is that, when we went to sign in at the meeting, the birth parents had signed their full names in the register and I saw them. I think I am the only person who spotted this - BM wasn't in any state to notice anything and I signed her out deliberately. I googled after the meeting (I know I shouldn't have, but I was quite shocked I knew this so easily, and tbh traumatised by the whole thing), and in less than a couple of minutes had their home address.
It is months since this happened, and I will not do anything with the information. I do not want to do anything that will affect the adoption being finalised, and there are very compelling reasons that mean I will never ever share this with BM or any other family member.
But, I feel I need to say to the social services, please please change your system so this can't happen again. If BM had seen this she would stalk the family. If it happens in other cases it could put children at risk or stop the adoption going through. I am sure that if adoptive family knew they would be deeply unhappy. 
So I'm torn. Do I say anything or not? Anonymously? Do I wait until we've had confirmation that the adoption has been officially granted? As an adopter would it mean that you called a halt to the adoption if you knew this? WSID?