Wow, Mychael, this is a tough one isn't it. I had a similar decision about six months ago when an aunt died. I sang at the funeral and had to decide whether to wear the kilt or not because many of the family members had not seen me in the kilt yet and I didn't want to "scandalize" or be a distraction for them. I did wear the kilt and it was fine, in fact better than fine because it was percieved that I was dressing as formally as I could in her honor.

In your case I would have to ask, was this former visit the first time Grandma saw you in your kilt? Could it be that she is a bit shocked and uncertain about how others will recieve you, and by extension, her? It's one thing when we choose to make the choice to wear kilts, but sometimes our families are just as nervous being with us as we were the first time we went out in public. If this is the case matbe a few trips out and about with Grandma so that she can become comfortable with the kilt would be in order. Then she might be more welcoming of your kilt for the birthday dinner. This becomes a matter of courtesy and concern concern for Grandma's feelings. I would probably grant her wishes.

If she's just being controlling (like some members of my family) then you have a very different decision to make, whether to be subject to her or not. Personally I would stand my ground in this situation, but that's just me.

I am around people of all ages at work and at church. Older people are a lot more flexible that they let on most of the time.

Jamie