I agree with Vicki. I would talk with the adoptive parents in a non-threatening setting...like a church or other public place. I would also have a mediator for your sake. I imagine your dtr's adoptive parents are wonderful but sometimes people can misinterperate things that are said. You may say one thing but they interperate it as something totally different.
I would also suggest meeting with them without your dtr there first. That way they can go home and tell their dtr they met with you and you are nice. Then she can decide if she wants to meet you.
Also---I wouldn't "friend" your dtr on fb just yet. That may come across as too strong to the adoptive parents and make them too nervous to really want to meet with you. They may think that you are going behind their back when in reality you aren't.
This is all my opinion and being an adoptive parent how I would hope our son's biological parents would do to us. The biological mother in our case opted for a closed adoption and didn't know who the father was.
I hope this helps. Keep us updated on how everything is going, please!