Glad you found the suggestions helpful, Amelie.
As for TMG being Silly, as Jim tried to explain in his first reply, they are showing as blood relatives because YOU assigned the parent/child relationship tag as Primary. That Primary indication is the only way to define a blood parent/child relationship in TMG. The "name" of a parent/child relationship tag has nothing to do with telling TMG that a relationship is blood. If you assign it as Primary, then you are telling TMG the relationship is blood regardless of the name of the tag. It really is that simple.
There has to be a way to single out one pair of parent/child relationships. A child (currently) can have only one blood father and one blood mother. Some user could create multiple TMG "-bio" tags for a child, linking that child to multiple (possible) fathers. Which one among the many is truly the blood father? It will be the one assigned as Primary regardless of the others also having the "-bio" name to the tag. So in your case if you create a "-Ado" relationship tag but assign it as Primary, you are telling TMG to ignore the tag name and consider this parent/child relationship the blood relationship.
Hope this helps explain what you are seeing.