If YOU'RE having difficulty following what's going on in parts of what you wrote, not to mention I am too and I've been using construct for about 5 years, I think it's not a good idea! Construct is supposed to be intuitive and simple, and I think else should be that way as well.
Another problem with option 2 - what instances would it select the inverse of?
- Sprite x < 100
- - Sprite2 x < 100
- - Else
Would it invert the selection of all objects that have any selected instances? It just seems... messy and hard to control somehow.
What if, for another option, there were more controls like the 'pick all' condition? Something like 'invert picked' and then an object selection box so people had more control manually?
I understand why you don't want to have multiple elses or multiple else modes, but I personally would want it to work like this:
Have a parameter drop-down menu (or two elses) so you could select between "run only if the above event doesn't run" and "run anyway" - neither of which do any picking, and then are combined with the 'invert picked' condition above. It's as simple and flexible as I can think of.