What causes family to be denied?

In Aman's case there were multiple family members ruled out immediately. Maternal Gma lived with biomom and was part of the MBP problem. So she was disqualified. Mom's partner lived with her and was disqualified. So was Mom's partner's dad. They all lived in the same house and contributed to mom's MBP problem. Mom's partner's mom (so like a grandma) Was disqualified because she had a history of CPS involvement with mom's partner when she was a child. Multiple other family members live out of state and are estranged from bio family. There was also a former foster mom from a neighboring state where Aman lived for about 18 months, and she wanted to foster him (Now she has asked to adopt him as well). She has been ruled out because she lives out of state and could not do fostering due to not being able to support RU from that far (for visits etc). Now they did look at her for adoption, but I think she is being ruled out since I have had him over 1 year, and AMan was an infant/toddler so he doesn't remember her.