Thank you Vinod,
I already have that module installed, but not sure if it solves my problem.
For example, using that multitenant management module I have configured
Tenant 1
User LR
User BM
Tenant 5
User AF
User MG
User LR
Following on from the example in my first post, I note the following:
1) All users, across all tenants, can login to all apps. This isn't the desired behaviour described in my first post.
2) Tenants 1 and 5 both share a user with the username LR. Why isn't unique username/password combinations enforced across tenants.