Hi there. To be honest, I wish I'd had a few more rules when I was that age. In the late 1960s when my older siblings were just 5 and 6 years old, my parents had my brothers on chairs washing dishes and my sister was helping with dinner. When I came along everyone did everything for me, and I never learned responsibility until I was an adult. By that time, I made a LOT of financial and personal mistakes.
I think your son and his wife are doing the right thing in teaching your grand daughter how to care for her own possessions and take responsibility to do some things for herself.
Keep sewing for her, though. I am sure your granddaughter will appreciate it. In fact, why don't you have her over every once in a while and teach her how to sew? It might prove to be a nice time for you two to bond.