Isn't this just taking the long way around?
Necromancy Angels cherishing their descendants is definitely a tall tale; even Harvey stamped his approval that Necromancy Angels don't treasure life—they are bootleg necromancers. Besides, how could mages who fear death have so many considerations?
So we need to think about it the other way around—it's not that the Necromancy Angel is refusing the inheritance to their descendants, but that the descendants have always been avoiding the ancestor's machinations!
Following this logic, the Necromancy Angel would surely transform their descendant into a suitable vessel for possession. So, what kind of vessel is most suitable for a spirit to take over?
First, she should be very mentally active but lack personal will;
Second, she should be extremely spirited but devoid of personal emotions;
Ideally, she should be born into a vast inheritance, allowing the Necromancy Angel to quickly regain its former strength.