this is exactly what I do also. this way no one is excluded or hurt. that MIL was very rude and very disrespectful. I am very much over weight and my cousin loves to point it out every chance she gets. Often she tries to hurt me and embarrass me in front of others. For example, a while back some of our church members were dressing up as different Bible characters to represent that character in a sermon being made. The sermon being, "Talking with Bible characters" I was Noah's wife.
While we were down stairs going through the trunk picking out our costumes one woman was holding up the clothing pieces for others to choose from. She held up a very large tunic which would have fit several of me in it. My cousin, laughing she said it, grabbed it tossed it at me and said, "oh this will fit Susan fine" The woman a friend of mine, turned red and grabbed it back and handed me a more suitable tunic. Nothing was said, but it sure was a tense moment. Guess there is all sorts of rude, uncaring people walking around, so called family members includes.