DH's uncle was convicted of child sex offences - indecent images and videos, including "extreme". He got a suspended custodial sentence, on the sex offenders register, and a sexual harm prevention order (I don't know the terms of this).
We found out before it went to court because SS and police contacted me for safeguarding purposes. DH and I assured SS that we would safeguard our children by not seeing the uncle. Also turns out his wife had known for months - since the police raid - but covered it up to the family, saying that devices that had been seized had been lost etc - but her covering up is another matter
Anyway what I take from that is that I can't trust her judgement either.
Now MIL (sister of the aunt) has unexpectedly received some money and wants to treat the whole family to a Christmas break in a lovely rented house. MIL is waiting until I'm out of the room and asking DH to contact the sex offender "because they're suffering" and to all spend Christmas together because "they've had a bad year so far"
DH has given a vague non-committal response.
I think they've all taken leave of their senses. They've not only accepted this "man" who likes to watch babies and children being sexually abused and raped, they're trying to make life better and more enjoyable for him 
I don't want to see the uncle - possibly ever, who knows - and I don't want my DCs to see him.
I will do everything in my power to block this - taking the kids away to another location if I have to - but I would like to know where I stand legally.
Are people on the sex offenders register even allowed to stay somewhere overnight with children? How would I even know if the terms of his SHPO prevent it? Would I have to speak to SS or police if I needed support in safeguarding my kids from this man?
And most importantly - am I legally allowed to forbid DH or anyone else from taking my DCs to see this man?
Thanks for any advice or pointers.