How to list property to set up a joint tenancy?

I have a simple question (I think): I have 2 different tenants identified for my property and want to put them on joint tenancy agreement. Do I list the property as a flat OR a room in a flat? If I do the former, am concerned both can’t apply and if do the latter, am concerned I will end up with 2 separate lease agreements.

FYI- both have been reference already.

Have sent a separate msg to Open Rent but am in a hurry and hoping someone else can answer!