A: Here is my perspective on the issue of your mother-in-law's wishes regarding how her grandson addresses her: I think you would have good reason to interfere if your mother-in-law wished her grandson to call her by a name which was clearly offensive or bizarre. But the name she has chosen--although perhaps unusual--is not a public disgrace. Thus I think she has the right to pick the name by which people address her, including her grandchild.
The problem seems to be between your husband and his own mother; as you have said, your own involvement is mostly by "default" because of your sympathy for your husband's feelings. But if he has an issue with his mother, I think I would suggest that the two of them work this issue out between themselves. Surely they have had some practice at this fine art. Dad and his mother need to hash out this issue, and then declare a mutual peace with the solution (even if someone is secretly unhappy with it).
It is important that your son be left out of the struggle. If you habitually refer to his grandmother as "Grandma," then your son is naturally likely to adopt this name in speaking about her and in addressing her directly. Then she will correct the boy, and he will be caught in the middle of the grown-ups' dispute. Sticking your offspring into the midst of a conflict of this sort is not doing him any favor. And I do not need to remind you that there may be many other similar tastes and activities in which your mother-in-law may have ideas that will not align themselves with yours. So setting a precedent of adult discussion and resolution of these issues before sticking the youngster into the battle-ground will be crucial.
Elizabeth Berger MD
Child Psychiatrist and author of "Raising Kids with Character"