It does not matter how much you leave someone to appease them - it all boils down to how much you leave and whether or not they are satisfied with it.Unfortunately leaving a relative a small amount of money (in comparison to large amounts left to others) would not protect your wishes from being challenged in court by a vexatious claimant.
In any case, it is not a matter of leaving 'something' to someone to appease them - after all is said and done they cannot just demand a part of your assets without it going to court to be finalised. IT TAKES MONEY TO CONTEST A WILL and that can amount to a great deal of money to the one contesting, which may or may not be the right outcome in the end as it could cost more to contest than to just let it go.