Good topic....sometimes it's good to remind ourselves what actually works.
For kt - humor & redirection are two of the best tools I've learned to use. I also use time to remind kt of her responsibilities, when they need to be finished & then give her time for questions or ask for help. I'll take that over any meltdown.
wm - again, humor. However, wm needs things written down for him in a clearly defined step by step manner.
Nine times out of ten, the tweedles have learned to negotiate & to ask for help. They are now of an age where I sometimes refuse that help & let them know this is something I know they can handle.
Thanks for starting this thread - I will be watching it closely.