A promotion component within another promotion not supported

Hi,

We have a scenario where there is a promotion product offered to customer at site level. There will be a promotion instance at each site location and there can be n number of such promotions. Above all these promotions will be a group level plan(another promotion). We need to maintain some kind of linkage between the group level promotion and the site level promotions. We were trying to explore the option of having child level promotions for the above requirement so that the promotion instance Id can be used for linking all of them.

Steps to reproduce:
1. Go to Administration products -> Promotions