A multi-site install requires 1-SITE per site on the server. But! You can mix subscriptions;
EXAMPLE: If you purchase (1 SITE | 10 FORMS), you can mix the subscriptions like this; (3-SITES | 8-FORMS) or (10-SITES | 1-FORM)
However you want… Just let us know how to adjust your license.
Let us know if that answers your question as we remain at your service.