Pages display advice needed

Hi – I’ve been searching everywhere and I feel like a dolt for not being able to find the answer to this. I’m looking for two widgets – one which displays only parents, and one that displays only the children of a specific parent, when that parent is selected. So if I had three parents: 1, 2, 3 and each parent had three children A, B, C it would function like this:

– When no page is chosen, the parents-only widget will display all parents: 1, 2, 3. the children-only widget does not display at all.

– When a parent 1 is chosen, the parents only widget continues to display all parents (1, 2, 3). The children-only widget displays only the children of parent 1: 1-A, 1-B, 1-C and not any of the other parents.

I want to put these into a three column theme with one widget on each side.

Thanks so much in advance for what I think is much easier than I’m making it. I’m sure that such widgets exist, but everyone that I try doesn’t seem to work, or perhaps I’m using them incorrectly.

Warmly,
Rick