Personnel Availability

Hello,

New to Filemaker and new to this forum. Hoping someone can help me out.

I am working on a personnel planning system with, among others, the tables Employees, Shifts and Availability. 

tblEmployees has fields like Employee ID
tblShifts has the fields Employee ID, Start Timestamp, End Timestamp
tblAvailability has the fields Employee ID, Start Timestamp, End Timestamp and Status

When in the layout Shifts I want to open a portal in a popup and I want this portal to be sorted by Availability and I want the portal rows with employees to be 'greyed out' when status = 0, green when status = 1 and normal when no Availability is given.

I basically need to know which records from tblAvailability match records from tblShifts and then which records from tblEmployees match records from tblAvailability.

How do I go about this? Do I need SQL?

Hope this is a somewhat clear question. Many thanks!