User Based Security in WCC

We have a requirement - to only allow specific named users access to specific folders in WCC (UCM).

Specifically I have a number of contracts which are only allowed to be viewed by people who are on the panel for the specific contract. We have hundreds of contracts, so we don't want to create a group/account for each contract - based on who should access the contract documents.  But we would like to be able to restrict folder access (by user) to named individuals as opposed to a group/account.  Is there a way to implement this?