1 . Possible to assign two or more different details tables to one grid?
Yes there is no limit you can have infinite number in infinite level of nested grid.
2 . have conditional details tables ?
Read this doc to learn how to access nested grid. Telerik doc
Test the nestedview name => do your control.
3 . have conditional details tables depends on master's selected row ?
Ok i just dont get what you want to achiev. But if there is some logic you can do it with the previous tip.
4. I just dont get it now ..
All this for a theme manager ? Ihave never done a theme manager ben i can see one on every telerik demo.
I am pretty sure you can find some info.
I can't help you more with so little information.