Highlight or colour a cell or cells based on cells in another range.

I think you need to number your seats with a unique reference, eg the row number and the seat number - I've put a few examples in row 5 of the attached file. I've also applied a named range "Seats" to columns E and F of your First Show sheet, and put some fictitious data in there which follows the numbering convention.

In the Seating sheet I've applied conditional formatting to the cells C2:L2 using this formula:

=COUNTIF(Seats,C2)>0

which turns the background red and foreground white (and bold) if the seat number appears in the Seats columns. You need to extend this to the rest of your sheet.

Hope this helps.

Pete