For aprox 5 hours. DH who can be a wuss at times thinks I should leave it, & maybe keep an eye next time - we've had similar happen before with the siblings pretty much forced in DD for the duration.
The youngest sibling was behaving very badly out of view of the adults, sweetness & light in view of the adults, they were spitting at DD, hitting & kicking her, she has bruises coming up to prove it.
It's a small get together, not a big party, 2 siblings & a cousin, DD has health problems so gets exhausted easily & to my mind this would be a lot for an adult to deal with & the parents were taking the pee. DD did try to speak up to the DM & ask for help, let her know that the 3yr old was playing up & she had, had enough, she's polite, so obviously wasn't forceful enough, as the DM just brushed it off as "no, no, she's fine & carried on chatting & drinking.
In fairness DD idolises the 1 yr old cousin & he's never any trouble, so she's happy to keep an eye on him & looks forward to seeing him, but still needs a break, but where's as she's happy to play with the others too for a while, she resents that the DM pushes her into it & presumes she's happy to look after them too & brushes off polite protests
AIBU to want to send an email tackling this once & for all ??