Going only what you have told us so far (missing facts missing,
and with any unstated ifs, buts, and variables not allowed for),
as a general proposition, if it is clear who the intended recipient is,*
then, absent any other factors, there is no
prima facie impediment to the gift.
For example, if the words are "my grandchildren",
and there were, say, two when the will was made,
but three of more by the time the testator died,
then absent any other complexities, it means all of them.
Where this can be a problem is when the text says
"my grandchildren X and Y", but Z was born after the will was made.
The question will be, did the testator intend to make gifts
to
all his grandchildren, and named the ones he had at the time
(perhaps out of some sense of formality) or did he really mean just to those two?
This takes you into the realm of a legal concept called "testamentary intention".
As a general rule, a court hearing a will dispute will look for evidence
of what the deceased intended, even if that's not literally what is written.
Some examples of where this can become contentious:
- Sometimes, you have several siblings, and one is estranged from the other(s).
The estranged one simply doesn't have anything to do with the family, sometimes for years.
Sometimes, the non-estranged relatives can have a problem with sharing
a legacy with a relative with whom they are not in contact; or
- Sometimes, you get one or two relatives who claim to have
"done all the work in the last few years", and do not feel that another relative
(who may have contributed little if anything) should get an equal share.
- Sometimes, you get a relative's spouse who, regardless of circumstances,
pushes the "But you've done all the work, so you should get more" angle
- Sometimes, descendant relatives have a problem with more complex family relationships,
such as the deceased's step-children, or the deceased's de facto's own children
(so you can get a dispute between "his but not hers" and "hers but not his").
Sometimes, this can include other relatives where, on the facts, and sometimes over many years,
the deceased has been, say, a grand-parent like figure.
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* whether that's an individual, or as part of a group or class of people