Filter Table Entries In Another Table

I made a version of this, but it there may be a cleaner way to do it.  Parent table "Employees" in your case Departments, has a formula-multi-select field that would populate in my case "crew members"  your's would be department members.  Then on my "timesheets" table when you select who is making the timesheet it has a multi-select lookup that pulls all the values in from that formula-multi-select in the parent.  My problem is it does not show all the people selected, you have to open the dropdown and look to find out, but you can check or uncheck values in that lookup field before you save the record.  Basically it gives you the default selection of multiple values for that field based on the lookup and then you can edit your choices before saving.  Hope that helps?