do your parents interfere with your parenting?

[cacoa]

I'm currently living with my parents till we move next year (could not afford otherwise).
My parents constantly interfere and undermine my parenting. if i say anything to son (16yrs) they will "its okay" or "don't worry" "never mind"
when they don't realizes I'm trying to make him realise or learn something.
its driving me insane and into despair. I hardly talk to my mum much as i keep telling her she interferes too much with my parenting directly to him, instead of telling me 121. When she does tell me anything it is always to criticize and complain about me.
Even when son shouts at them they don't see it as bad and don't stop with him. Even simple things like family dinners are not peaceful, as they keep treating him as a toddler "xxxx would you like this" constantly, he gets fed up being asked to eat such a dish numerous times and tells them off in loud tone or abrupt manner. And the same will happen next day :( My folks don't get it to back up a bit.
He plays us all off with each other now.