I'd definitely say no if you aren't comfortable.

However, (don't bite my head off LOL) I know with my MIL she knows how particular I am about my house and cooking and blah blah blah and when she was here she didn't want to step on toes, when I was sick she sent me to bed and told me too bad so sad she was going to take over even if it wasn't exactly how I did it. And when I asked her what I wanted done she was definitley happy to oblige but she too just wanted to be asked. I think especially with MIL's sometimes they feel like they are damned if they do and damned if they don't. So if in doubt just ask, if they offered to be there to help and you ask them to do something they really shouldn't object as thats what they are there to do and they will probably be glad you asked so that they know they will be doing something that you want them to do iykwim?

BUT if this is totally not your situation then thats fine I'm just offering a POV, one I didn't realise with Paris but came to realise with Seth.

*hugs*
Cailin