Challenging a will isn't something that can be done by just anyone. The law has things pertaining to a will set up so that only specific people can challenge the contents of the will. People or entities who don't have a legal interest in the will can't challenge it.
One group of individuals who has an interest in the will even if they aren't specifically named in it are those who would stand to inherit all or a portion of the estate if the decedent had died without a will. State law sets up a succession plan of people who can inherit assets if a person dies intestate.
Another group of people who can challenge a will are those who were named in a previous will but have been left out of the most recent will. These individuals would have to establish why they should have been named in the current will.
A third group of people are those who are in the current will. These individuals might not agree with the terms of the will. They need to be aware of the presence of a no-contest clause in the will. If this clause is present, the person stands to lose whatever he or she was entitled to if the petition to challenge the will is unsuccessful.
Challenging a will is a complex undertaking. Even though you have established that you have a legal status for challenging the will, you still need to establish that you have a valid reason for the contest. Simply saying that you don't think it is right isn't a valid reason.
Source: The Balance, "Who Can Contest a Will?," Julie Garber, accessed Dec. 29, 2017