They are difficult but I think seeing pils for either a day out - or - all day at their house a few times a year won't damage DC.
I think older DD has a good strong sense of things now, and has herself mentioned Mils comment of - for instance.."we don't have play stuff here for you because we don't see you enough" is a bad thing to say.
Mil has traipsed over all sorts of boundaries in the past - we have had so many ups and downs and low contact and more contact but we are back to low contact again now. Lots of reasons but over all they don't value or seem to care about DH, Mil only cares how much he loves her. When I met DH he was struggling with his DP. They are very controlling, fil is also madly controlling BUT makes more effort to be smooth than mil does. In fact when a poster on here said on a thread - google "grey rock " and narcissist I realised its what DH did to minimse himself from Mil at least. Whether fil is also one I'm not sure he just seems to do anything to please her. DH would never say personal comments, everything he said was neutral...and I know why now.
I personally strongly dislike the way the way they operate, and their values. DH would never go home to just relax, or hang out. The atmosphere is not conducive to that. They are not violent or drug addicts but seeing dc more regularly I think at their current ages would be problematic to me. If they tried for example to take us to court for more access I would fight them tooth and nail.
However, in short doses the DC like going ( anything more regular they start to really protest) and the pils are on best behaviour to see them.
However, would anyone disagree that seeing the dc for days out or all day a few times a year would be fine. They saw dc with us at xmas, ( which was not fun and probably wont be repeated) then alone all day, on day out in March, one will probably go there all day in June then both again in August for a day /day out,.....after that maybe once more before xmas.
Personally I never saw GP more than that and never alone, pils always want hours alone with dc. Older DD is not keen to go and younger would rather she went....younger has always got on better there than older and I dont see why I should force older.
Personally I dont feel they can do much damage on those sort of time limits.....within very full active lives meeting all sorts of people, lots of friends over here and sleep overs...