Question : create a group administrator without the possibility of changing his quota

I am facing a problem, I am trying to allow to create a user who is automatically administrator of a group with a predefined quota.
example: user A is an administrator of the Company X group with a total quota of 20Gb.

I would like to allow the group administrator to create subgroups (Marketer/IT/etc…) with users without quota limit (up to a max limit that is equal to the total capacity acceptable by the folder).

Currently I know how to create a user as a group administrator except that he can modify his quota in unlimited.

do you have a solution to the problem?

@Quentin_Gosset Did you ever get a solution to this? It is the same scenario that I have come up against.

The group folder quota plugin works well, but makes it null and void if the user can just over change their individual quota or add another user with their quota.