Is there such a thing as an OLAP cube that can change the number of levels in a hierarchy without having to be rebuilt?
You will need a parent-child dimension, where each member also keeps the id of its parent; something like

Id; name; parent

1; world;null

2; europe;1

3; north america;1

(...)

123; france; 2

And so on. Whether your particular OLAP solution supports this or not?... that’s a different battle.