Needing help with Birth Mom

Hello everyone,,I am new to this site. My husband and I are in the process of adopting 2 boys that have been in our home for 27 months as foster children. I have known these boys and their birth momfor 6 years all together. My husband and I have 2 birth sons (19 & 2 yrs old) , and 2 adoptive sons ( 7 & 8 years old), and almost 2 more adoptive sons (15 & 9 years old). The birth mom is not really a bad mom, she just had trouble following what the agency told her to do. We get along with well with her. She has told both the boys this week that she will sign papers over so we can adopt the boys. We did tell the birth mom that we would let her have some contact with the boys. I told birthdays and holidays. She has also told both boys that they could call her anytime they want. The nine yr old wants to call all the time. I want us all to be a family. I don't want to get off on the wrong foot with this adoption. I know that she is broken hearted and so are the boys. My husband and I got married to have a family and to help other children out. I don't want to be married to her too or to be her mom. She told someone that if she had transportation, she would be coming to our church. I know that she needs to be in church, but if she goes to our church she would be going for the wrong reasons. My husband and I want to be a good Christian witness to her, but I don't want my life to be surrounded by her. Can anyone help us set this whole open adoption thing up right where she doesn't think we are bad people or our soon to be sons don't think we are bad either.