How do i get this formula to work using conditional formatting?=IF(ISNUMBER(SEARCH("abc",B5)),B5,"")

I am trying to create a scheduling spreadsheet on excel. In each column there will be a Workers name and in each row their will be time slots in 30 min increments. The formula:

=IF(ISNUMBER(SEARCH("abc",B5)),B5,"")

This works when i want to pair two employees together and have both cells relay the same information. The problem is i ONLY want this formula to work when it's triggered by the other cells text. In other words, i need the same effect still, however, i need it to work within conditional formatting so that i may still use each cell for adding work descriptions to the cell if they are not paired.