"I wouldn’t have thought it was that uncommon for adult children to be left nothing, if there’s a spouse alive."
I don't think it is uncommon. But often, the agreement between the spouses is that the remaining spouse will leave money/assets to the kids when that spouse passes.
"So he, who had done so much for her and her sister over many years, was the only one who lost out financially. "
This is sad, V3ra. But did the aunt leave any money to her other nieces and nephews or only DH (besides him, you only mention great-nieces and great-nephews). IOWS, did she skip over other nieces and nephews to leave money to their kids? Perhaps it's b/c DH did so much for her that she left him the money instead of your two children?
If it's any comfort, I don't think you and yours are the only ones who were ever disappointed in an aunt's decisions about inheritances. I've heard of cases before where one niece or nephew did more for a childless aunt, only to find that she divided her assets up equally among all her nieces and nephews in her will. Or that she left everything to a favorite charity.
As for estrangement, I don't see, people, how anyone can expect an inheritance from a parent they have CO or be shocked if they find out that parent didn't leave them anything. If they want nothing to do w/ that parent, it seems to me, they shouldn't want their money/assets either. But I admit, I haven't been in the situation, so, ananimous, I don't know how it would feel.
In fact, I agree that it would be preferable for the EP to try to find a way to mend the estranged relationship. But if that doesn't happen, EAC should not be surprised to find they have been cut out of the EP's will.