Cashier time log Lookup

Hi All

I must be doing something wrong - I end up with circular reasoning.

I have attached a sample of what data I have.

Say at Till 1, there is 6 cashiers for the day, and I want to Validate data for till one (Selecting till 1 from the drop down), I only get one cashier's name and not all 6... And then how do i get a vlookup to bring back the start and] end of their shift.

(I struggle to insert the attachment - Hopefully it works) Looking forward to the help!!