We're on a break from the deprivation right now... was bad for most of the first 2 years, but much better now. But then we'll be back into it soon I suppose.
I don't know long term. For us, just making do and making things as easy as possible was all we could do.
And I'm sure it's not your fault - it's hardly unusual for young children to have trouble sleeping for one reason or another.

Maybe for your older girl you could try some sort of system or something to encourage her to stay in her own bed? I can't really offer any specific advice, sorry. Perhaps DD2 will go back to sleeping better once she's through the current phase...? (or do I sound ridiculously optimistic?)