Lots of history with MIL who is difficult at best.
She is coming to stay for a week at the beginning of December and she already has been moaning to other relatives that her awful DIL will make her freeze, by this she means not whacking up the central heating to 21 degrees as she does in her own home.
My 2 dc's and myself so not feel the cold much and we usually only have the heating on for a few months when its really cold, dh feels it a bit more but quite happily wears a jumper in the winter months, myself and DD really struggles if it is too hot and when we visit MIL & FIL we can not stay too long as its too hot.
I do not want to make her feel unwelcome, but also can not stand it being too hot, so we usually set it for 18 degrees, (which is about the most I can stand) MIL will wear a thin top and a very thin cardigan and then complain she is freezing and asks for a blanket. We have bought her thick jumpers and thick cardigans for Christmas, but she does not bring them to wear.
Where MIL is concerned my views are very cloudy, she is not a frail old lady, she is early 60's and very active.
I have always been of the opinion you can add layers, so AIBU and am in fact ill treating my MIL.