I am an amom to two children thru domestic adoption.
I have opened up both adoptions from semi open with no visits to open with visits.
My dd (4) open adoption is no probem. We have a GREAT relationship with her bmother and bbrother. Her bmother is older and understands the in's and out's of open adoption. Her brother (12) also understands the situation and my dh and I can't help but like him and find ourselves wanting to spend more and more time with him. What a neat kid!!!
My ds (1) open adoption is very difficult right now.

My son's bmom is still a teenager. Her first visit to our home was a surprise visit.

That was the first time I ever met her. She still catches me off gurad with things she will innocently say. I have to gently educate her as we go along and that makes ME VERY UNCOMFORTABLE. I'm torn between wanting to be her friend and also feeling the need to protect my "feelings of entitlement" to be my son's mother. We (dh and I) are struggling with this relationship right now but we are committed to open adoption. We want our son to have the same access to his birth roots as our daughter has.
My biggest mistake was thinking the first open adoption would be like the second. Each adoption is different as each person is different and in different stages in their life, which impacts in how they respond to us.
Whew...so if anyone has any questions that I can help you with, feel free to ask away!!!
((hugs))