More research that my husband and I are learning about are the semi-open adoptions.
Here is an article from Adoption.com:
Semi-open adoption is the practice in which information, generally non-identifying information, is shared between adopting parents and placing parents. Usually semi-open adoption consists of the exchange of letters, photos and possibly emails, either directly or through an agency or third party. Often, adopting parents will set up a post office box which letters, cards and photos can be sent and received. Unlike closed adoption, it is more common for placing parents to choose the adopting family for their child prior to birth. It is also not unheard of to have some pre-birth face-to-face meetings or for the placing and adopting families to spend time together at the hospital during and after the birth.
Semi-open adoption doesn't usually involve any post-placement face-to-face visitation. The children involved don't normally have any direct communication with their biological parents. Like closed adoption, once a child reaches the age of majority in their state, they have the option of searching for or being searched for by their biological family. However, unlike closed adoption, those involved in a semi-open adoption usually have access to some basic information which can assist in the search process.
As adoption has evolved over the course of the last decade, adoption practitioners are finding more and more semi-open adoption arrangements in situations that routinely would have been closed, such as international and foster care adoptions.