Lists

I think I'm getting used to the lists but I was wondering if there is any way to show those people with only one parent (you can do it for parents or no parents but how aboult only one parent)

I don't think there is a way, but is there a way to run a list of those that have something in the overview, or even more important nothing in the overview

and finally, is there any way to get the list to show more than 5000 people.

p.s I keep getting a "overflow error" every time I run a list, I have plenty of memory, am I the only person who gets this? (my computer or the program?