1- the inconsistency is when in families where parda is not observed among other NA mehrams this is called as an issue. But yes otherwise, it’s a condition that has to be satisfied.
2- inheritance no, gift yes. But it was a two way street so ppl who were raising an orphan did not get access to the assets left for the child by his parents, additionally it will decrease opposition in the family for someone raising an orphaned child due to family members fearing for impact on their stake in the inheritance.
Similarly, in the example u have of ‘aaq’ … A parent has full right to gift anything to anyone to a point that nothing is left for the kid they don’t want anything for. It’s all roundabout stuff but sadly the essence gets lost. Which is too broad to cover here.
I have shared it on this site before but someone in my sisters social circle had adopted a girl. The adoptive parents died in an accident, and the deceased mans brothers swiftly moved in to take the inheritance, since the property and assets were mostly in Pakistan, leaving her with nothing. Luckily one of the deceased friends was a human being and took the girl in his family.
Now technically if they are not observing purda, they are religiously more wrong than the brothers who took everything.
Makes sense to you?
Point is that the conditions exist for a reason, people need to understand
The people with a claim on inheritance due to their relationship do have the ability to give up their claim in the benefit of their brother or sisters or fathers adopted/fostered/whatever term child.