hmm i've just been thinking.

ok advertising on a vehicle is going to start and finish. and then another one start start to maximise revenue.

If I change the Start and End/Due Date for the next advertising. It deletes the X's from the Calendar bit and complete teh new bit.
It would be beneficial to keep that so can keep track of who advertised and when.

Unless when one is ending I could somehow send to Archive the info on that truck to another sheet and simply go ahead and change the Start/Due Dates for the next advert

Archive Reg, Start, Due Date, Duration and I enter who advertised manually