Can a member work at more than one location or department?

Yes. Tick each one on the Assignments tab of their profile, and they appear on every one of those rosters.

1. Click your profile picture in the top right, then click Members, then click the member.
2. Click Assignments.
3. Tick each location they work at. Click a location's name to see its departments and roles, and tick the ones that apply.
4. Click Update.

Note: Every location you tick needs at least one department ticked, or Timble won't save.