Where to present the functionality of pairing two entities in an Administration System

Question

In this example Administration Platform, you can have users and user groups. You also have a page where you edit the users and a page that you edit the groups. And of course, you need to pair the two which can be done in two ways:

• You can have a listing of the users in the group page (or not) and be able to add a user to it.
• having and option in the user's page to add him/her to a group.

Is it a good practice to have the functionality in both the pages? Is it preferable to have more that one points where you can do stuff, or it going to cause confusion/frustration to the user?

If it should be in one of the two places, what is the common practices in one-to-many relationships, adding entity to group or group to entity?

The product is an Administration System and the user is supposed to be trained.

Answer 1

I think both ways should be provided as they are related to 2 different use cases:

• you create a new group, you're in the group page, and you want to add a number of users at once. The UI shouldn't force you to switch to users management page to seek each individual user and add them to the newly created group.

• you create a new user, who needs to be added to a number of groups. You should be able to associate this user to any group from this user's page.

The relationship I described here is many to many. Even if the relationship is one to many, the shortest flow is to pick the group when creating the user, rather than create the user, then having to switch to groups to add the new user to the relevant group.