I'm trying to construct a WeakAura, that combines two(or more) CD's into one.

For example: HTT and SLT. I only want to see, which of these two ability comes off Cooldown next. And only after one is ready again, I want to see the remaining time left on the other CD.
I'm only managing to prioritizing one over the other. Can someone help or is it not possible to do that with WA?