OK, that bit's done now too, so now for the really fun bit.  Every now and then someone pops off for a holiday or something and as a result doesn't have to pay a certain bill, since they weren't there.
Is there any way of putting in exemptions so it won't apply a certain bill to a certain person if we tell it to?
Hey neat! Just noticed I got a little cake by my name. Happy Birthday to me!
 
Edit: Thanks Fyron!  Couldn't be bothered re-aranging everything (work on my birthday? A pox on you!) but your formuals still worked nicely even with the extra clicking.  
