Assign a user to access only specific subscriptions
Currently, there is no option to selectively assign a user to access multiple subscriptions.
The available choices are limited to granting access to either a single subscription or all subscriptions.
Plesk Tech Support
shared this idea
As on a subscription level the security model does not allow to add a role user to one subscription who can access another subscription, too, (that would break the security model, because then users could create their own permissions to access other users' subscriptions) it will not be possible to add a feature where a user inside one subscription can be allowed to access other subscriptions.
But: You can assign multiple, selected subscriptions to the same owner (user), so that when that user logs in, he sees all the subscriptions assigned to him and can access the subscription of his choice with a single user login. In order to assign a subscription to an existing user (subscriber), click on the "Subscription" menu, check the subscription(s) that you wish to link to another subscriber and click the button "Change Subscriber".
-- PD