My mother recently developed a very annoying habit of telling our relatives that the presents I buy them are from me and my sister. My sister doesn't bother with them. I do. I spend my own money on their presents, which my sister makes no contribution to. When my mother tells them these things, my sister never bothers denying anything or offers to contribue to any future gifts seeing all my presents consistently being presented as our gifts. In fact, she seems quite happy for it to continue.
I understand that my mother wants to make my sister look good but I am not particularly happy about her behaviour. Am I being petty?