My friend, who is a nurse , treats her PA MIL like a rather senile patient.
" yes dear, I'm sure you're right "
" really, that is interesting " ( in a tone that means how boring )
So similar to thumbs . She ever gives her any personal information eg if she's worried about how their teenaged DD is coping with exams, she would NEVER tell her MIL, she just talks in bland platitudes
" oh yes, Emma has her mocks right now, she's coping fine / it's a stressful time for them all " etc
Everything is fine / good/ great . MIL is a drama llama so gets bored without a juicy piece of gossip .
Her MIL is very manipulative , so if my friend said she WAS worried about her DD, granny would go to the girl and say
" your mother is worred sick about you , how can you be so lazy and not study, you will waste your life ! " etc. then say innocently
" I was just repeating what you said / doing it for her own good "
Also my friend gets her DH to do most on the interaction with his mother, which is only fair . He's not allowed to bugger off to work and leave her with the hassle ( which he would do if he could )
Another friend has a lot of headaches when her diffult MIL comes round ( the old ones are the best ) .