Oh that's no good at all, how frustrating for you.

BUT you mentioned you could take a step back on the weekend and have a listen in to how your husband manages her. Maybe you could hand her to him and take notes of some sort. How does he calm her, is it the tone in his voice, does he laugh her out of things or take her tanties very, very seriously? For eg.

Its a bit the opposite here. Its almost like my son and I have the same brain (well we are both Geminis!). I totally get him at all times, he is prone to tanties, screaming and such but I always seem to know what he needs or what caused it. Although when he was a baby Dp was heaps better at settling him than I was..

For eg - DS can't stand to be hurried or worried. Its his main trigger, even a throw off comment will have him asking questions for hours. I give him directions to what we are doing, what he needs to know. I give it plainly and not too much information.
Dp is always hurrying him up, never gives him notice, always interrupts what DS doing. He uses stupid slang all the time and gets frustrated when DS asks him what he means, repeatedly. It drives DS spare and Dp can't see what the problem is.
I get it because that's what I'm like.......the problem with us is that Dp refuses to see his approach isn't working with DS and wont change it .

It might be tiny things, so do see what on earth it is your DH does and see if it works when you do it???