CBGallery multiple owners

Wouldn't this show the album on any users galleries with the "shared" asset output?

We have members that would collaborate with some people on some projects and other people on other projects and each album would need to be only shown in the galleries of the users involved.

User A + User B collaborate = Shared album 1, shown in only A & B profile galleries.

User B + user C collaborate = Shared album 2, shown in only B & C profile galleries.

User A + user C collaborate = shared album 3, shown in only A & C profile galleries

Yes, it will show the shared album on every profile as that's how Asset works. Asset determines what is displayed. If you need user specific Assets you have to use substitutions, which the Asset parameter supports. For example you could have a field that stores the users collaborator user id. Example as follows

Field: cb_collaborator
Type: Integer

Then for User A they'd have User B's user id. So lets say for example that's 621. Now in Asset you can substitute that in as follows.

profile,uploads,[cb:if cb_collaborator!=""]profile.[cb_collaborator][/cb:if]

This is going to show every profile gallery entry of User B on User A though unless again the album has a unique asset. So for example if the album has something like "shared.621" then you'd have the below.

profile,uploads,[cb:if cb_collaborator!=""]shared.[cb_collaborator][/cb:if]

Since this is project based through you probably need a value that both User A and User B would have. So you'd probably have the below.

Field: cb_project
Type: Integer

profile,uploads,[cb:if cb_project!=""]shared.[cb_project][/cb:if]

Now both User A and User B just need to set cb_project to the same value.

If user A works with each user upto Z and each project needed its own album, would he have to have 25 different "project" field intergers so that each album is displayed on the correct users galleries?

a + b = project 1
a + c = project 2
...
a+z = project 25

What is a project? It would be significantly easier to just have an entire gallery dedicated to a project instead of trying to link them to peoples personal profile galleries. If a project is for example a CB GroupJive group then GJ groups already have galleries powered by CB Gallery by publishing its necessary system action in CB Auto Actions. If it's some third party extension you can likely load galleries on the project pages using CB Gallery Module or CB Gallery Bot.

We work with models to create albums that they can showcase on their profiles. Sometimes the models will work together and both star in a photoset so we were just looking to showcase that album on both of their profiles.

Sounds like the easiest approach is to just upload to both profiles in that case. It's a lot of work to implement album sharing, which is not a planned feature in the foreseeable future.