K.M.
I understand what you're going through.
You have to put your foot down and demand he be raised the way you say. And, as hard as it is...you have to be consistent with EVERYONE.
I have it a little easier because my boyfriend IS on board with everything so, he will make sure his mom, my mom and everyone abides by our rules. We make it a team effort when dealing with resistance from the Grandmas. My 2 and a half year old son LOOOOOVES to wash clothes. And, my boyfriend's mother will create any laundry so that he can have his wish. Only, sometimes it will interfere with dinner time. I get home from work around 7PM and I want to spend quiet, quality time with my little family for dinner but, she'll have a fresh load in 5 minutes before I get home. I demanded that washing clothes has to stop at 5pm and that's final. And, its been the case for a few weeks now.
If my boyfriend's mother isn't doing something the way we instructed, he will take our son downstairs for the rest of the day. It sounds weird b/c its like a punishment to a 50 year old woman, but hey, its our way, he's our son and a reflection of US! No one ever blames a childs bad mannerisms or spoiled behavior on grandparents, only parents! Nip it int he bud girl! She's had her shot at raising kids, this is your baby and he is all of your responsibility.