There is a patch for that and its called "Make your own party" - specially for PotD thats not to much to ask because it doesnt require four people but any number between one and four. This content was designed to allow flexible parties.
If you chose the comfort that is DF to get smoother runs with more people, you also chose the risk of running into people who'd prefer to play the game in a different, but still legit way. If you are unable to deal with that properly - and from all that I can see Ama and her friends are (getting upset because someone doesnt help you to clean up your own mess? I'm sorry that I'm repeating myself here, but to me this sort of behaviour seems kinda... rude-ish. Maybe I'm sensitive, but it leaves that sour aftertaste that someone is considering themself more important than the rest - seperating from the group, having people waiting for your, so the whole group can progress and then you even go and pull more than you can handle yourself...? Maybe thats just me, but if you leave the group in PotD, I expect you to be able to look after yourself - shouldnt be to difficult, the place can be solo'd after all. If you're constantly making it clear that you wont consider my intrests but are instead banking on me to safe you all the time, I feel used - and I dont like that.)
I would like to see one of her parties live by now, tbh - just to be able to evaluate whos the real "toxic" person in question. We're always only hearing on side of the story - I'd like to see the whole picture by now. Different datacenter for me, will never happen, but still... as I just described the whole "help"-macro-thing can come off two ways: Ama chooses to picture it as the poor damsel in distress thats left to die - while for me it seems more and more like someone getting upset about other people not obeying them and using randoms in DF to their personal advantge - but maybe I'm a bit to extreme here now... still... would like to see that in action and judge for myself...