This is a question I plan on thinking a lot about in the coming years. I think it is a key part of having success in this area. The stakes are high. Too many children are currently stuck in the social welfare system. While many are there for completely valid and necessary reasons, turning them into families is a serious challenge most people are definitely not ready to face.
Anyone who has read my previous posts should quickly know that I do not believe that success is simply a matter of having enough love. Two things work against that. First, these children are often connected deeply to the family they were removed from. That is ultimately a good thing, but it complicates their ability to join another family. It may even prevent it completely.
The connection they have to their birth family also can develop a fantasy tone over time, as they only remember the good things about that family and even add other things, making what they don't have "perfect" while they face the many challenges of living in a real family, one that holds them accountable and pushes them to grow and heal. Even being honest about things with them, especially as they get older, can seem like only badmouthing of the birthfamily and can end up stirring up resentment instead of understanding and healing.
Complicating this is the fact that all the paperwork by social workers may not be completely accurate. Even items that are may not fit with their fantasy memory of their birthfamily, further convincing them that you are making things up to harm their relationship with their birthfamily.
Add to this the lack of truth of what happened they may face if they do reunite at some point with their birth family and you can have a real mess. Few birthparents will want to admit to the material you received about what happened (from CPS and related sources). They may very well tell the children that all the things said about them (the birthparents) were made up lies, putting even more strain on the adoptees connection with the adoptive parent.
In fact, many adoptees already distrust their adoptive parents, so such proclamations of innocence on the part of their birth family can reinforce the view that the adoptive parents are really a part of the problem rather than the solution.
I wish I knew how to get past this. Hopefully I can figure some things out in the coming months, but I definitely believe what I have written here and it is consistent with my own experience.