"That's not how we do it at Daaaads," I hear. Great. So this split family living isn't always the easiest. Being a parent of pre-teens isn't the easiest of jobs under any circumstances. But what on earth do you do when they are shuffling between two parents who have two sets of rules.
Well my best advice is IF YOU CAN, talk to your ex. Discuss some of the basic rules like bedtimes, curfews, homework habits and so on. If at all possible agree to some consistencies. If you can't because your ex thinks that when you have such conversations you are trying to "control" him/her, then don't.
Instead just calmly explain to your child why the rule is the way it is at your house. Explain that in society there are different rules at different places all the time. Like at school you can't chew gum or maybe wear shorts, but at home you can. I also am a firm believer in not setting too many rules, as we all know rules are made to be broken.
So unless it is really causing detriment to your family or your child, sit back and see if maybe you are the one being unreasonable. Many of us dig in our heels just to spite our ex, and if we really step back we will see that occassionally it is us being out of line.