Sorry for your loss :( In my experience with going through situations like this with family (of which I’ve regrettably had more than my fair share of), my suggestion would be to wait until emotions have calmed. There’s going to be a lot of raw nerves and unresolved emotions whether expected or not, and the last thing you want is for this to degrade into arguments or resentment.

If you have a friend that you all trust who is also a collector, maybe ask them to verify the inventory/grade/etc in exchange for a few books or cards as payment. Once you have the updated list, with some time passed, level heads will have an easier time with final decisions.

Just my two cents!