@bryan62 , while agreeing with my colleague @Vanessa A , i have a slight different nuance to the situation.
(a) I see this as a gift, with a delayed/ restricted possession. Thus it is effected "only when permitted" by the condition of her death.
(b) So the acquisition is by gift and no inheritance.
(c) However, since at the time the gift being effective, the donor's basis was stepped up to FMV ( under US laws applicable to you ), your basis is FMV on the date of death i.e. when the "possession/gift" was effective.
Note that the my conclusion leads to operationally the same as that of my colleague except that I recognize that this was a gift.
Does this make sense ?
Is there more I can do for you ?
pk
