Hi, thank you so much for your help so far. The CF to grey out looks to be working as its supposed to, just as a note H15 and H16 wouldn't ever both be blank, H15 would always have a value.

Ideally I would like the yellow only to appear when the button is clicked, and to include the white cells within rows 5-55 and row 98 to highlight, like in the previous version you uploaded.