Different quota for external storage

It would be nice to have the possibility to set a different quota for external storage.
For example, I’m planning to add a SIA storage that is cheaper and bigger than my VPS storage, so to encourage the users it would be nice to set a low quota on the “home” and a bigger quota on the external storage (SIA in my case).

what about setting up 2 different groups… like “vps” and “sia” and grant different quotas for them?
and then put your existing users in both, letting them know that they can have more quota on the other one…
and keep fresh users from joining to “vps”…