Rotate weekly 1st priority cleaner for a property

I want to be able to rotate the list weekly so each cleaner has a chance to be allocated cleans as no.1 cleaner. I share cleans evenly at some properties. IGMS told me this wouldn't be a problem, but it is. It cancels all previously accepted cleans from the prior no.1 and gives them to the new no.1. It should only give any new cleans, or not accepted cleans to the new no.1 when I change it. Please fix! Thanks!