To avoid having his kids get away with murder whilst your kids complain that they have no rights, both you and your new partner need to first establish some rules and boundaries.

Make a contract.
Decide on the most important rules. Try and keep the list short with no more than 5 rules to begin with. Print it on a large piece of paper and display it in a prominent place.

The rules should be specific - for example, Everyone should be in bed by a reasonable hour is not specific enough and leaves room for disagreement. After all my definition of a reasonable hour could be 8:00 pm and your idea of a reasonable hour could be 11:30pm. A better way to phrase the rule would be All kids under the age of 14 need to be in bed by 9:00pm on weekdays and by 10:30 pm on weekends. Another example would be All toys to be picked up before bedtime instead of The house needs to be cleaned before bedtime.

Try and phrase the rules positively instead of negatively. In other words, tell them what to do, not what not to do. Instead of Dont turn the TV on until all homework is completed you could say The TV may be turned on once all homework is completed. A small change in your wording can have a huge impact on the amount of co-operation you get from the kids.

Choose your battles wisely. Do you really want to waste your time arguing over toothpaste tube caps and toilet seats left up? If it wont matter 10 years from now, forget about it. Save your energy for the big things.

Present a united front to the children when discussing the house rules. If the children sense that you are not united then they will begin to divide and conquer.

Let the children settle their own disputes. Resist the temptation to mediate and settle every dispute. The best response is to tell them to work it out themselves.

Support each other. An important part of establishing rules is deciding on the consequences if they are broken. The consequences need to be clearly spelt out, and the children must know that their natural parent will support their step-parent in enforcing the consequences.

The question of who is to discipline whose children always crops up. To avoid a situation where your step-child tells you I dont have to listen to you because youre not my mom/dad, you need to make it clear to them that both parents (both the biological parent and the step-parent) have the right to enforce the rules.

These few guidelines should make the step-parenting journey a bit easier.