slony is normally described as a master-slave replication system.

I'm sure I could set this up to try, but it seems easier to ask a
straight question on it. I'm sorry but I've not found previous Q/As to
answer this one simply enough for me to be clear.

Any table can have one source. That seems to allow me to setup links so
that:

System1.Table1 -> System2.Table1
System2.Table2 -> System1.Table2

Yes? Good. Will that work for inherited tables too? Can I have:

System1.Child1 inherits System1.Parent
System1.Child2 inherits System1.Parent

System2.Child1 inherits System2.Parent
System2.Child2 inherits System2.Parent

System1.Child1 -> System2.Child1
System2.Child2 -> System1.Child2

which is close enough to multi-master replication for most designs.

So if I ask for Parent on either system I get the same data (ignoring
the data delay complication for the moment) ?

Does slony also allow me to do this:

CentralSystem.ChildN inherits CentralSystem.Parent

System1.Table1 -> CentralSystem.Child1
...
SystemN.Table1 -> CentralSystem.ChildN

which is the central rollup scenario.

Best Regards, Simon Riggs