Where Domain is your Module name and User_Group is the association between the entity "user" (people you want to display) and group (of which these people are a member.
Add this as xpath constraint on the entity
Could you be a bit more specific? How is the user related to group?
Assuming you have an Account entity associated with a Group entity, you could use something like:
[UserManagement.Group_UserAccount/UserManagement.Group/UserManagement.Group_UserAccount = '[%CurrentUser%]']
Is this what you are looking for?