Hello to group!!!

I have worksheet where I have shifts for my employees.I have 5 foreman and
they make schifts for them.Sometimes they make mistakes and I wonnt to make
default workscheet function that they make less mistakes.For example if one
of may worker work night schift for 6 days I woont that they can not put in
worksheet
another night schift.
Thanks for any help!!

best regards
lopina