Need some advice on how to navigate the following.
Firstly, SIL and I have a strained relationship. We don't really get on and things have been said by her to me over the years that I've now opted of out of having any contact other than when we go to see the in-laws, which we are doing over Christmas.
A few weeks ago MIL came to stay and she was on the phone endlessly to SIL who was going a bad time - this bad time has been going on for 3 years. DH and BIL became embroiled too and over the weekend they spent hours with her on the phone. It was basically over her ex-husband asking to have their kid for an extra night a month. However, it all blew up resulting in the entire house being woken at 3am by her wanting to talk and then everybody up until 5am.
MIL said she is tired of it all and had come to see us for a break, which didn't happen as she ended up on the phone to her for most of her stay.
Anyway, on FT MILs other grand daughter asked could our DD have a sleepover at their house over the Christmas holidays. Given SIL's behaviour over that weekend and later being told SIL isn't sleeping, taking care of herself etc, I said later to MIL that I didn't think it was a good idea and I didn't feel comfortable with DD going. MIL agreed and said she understood.
Yesterday MIL called DH and said that SIL is now fine to have DD for a sleepover. Given I am never told the entire story, I don't feel DD should go for a sleepover there. DH and I have had words about it and I know with the MIL and DH on side, I am going to be bamboozled into something I am not comfortable with. Any tips on how to navigate this as I will undoubtedly be the villain.