A new blended family can bring up many issues. How step-parents deal with each other's children, who handles discipline, establishing rules -- it can be tricky. Children may react to new siblings or parental figures in a variety of ways depending on their age, temperament, how discipline is applied and relationships within the blended family. Of all the many issues that can arise in blended families, not sharing is probably one of the most common -- and one of the most frustrating.
Present a united front. To encourage siblings in a blended family to share, and to get along in general, it helps if the parent and the step-parent are on the same page. As difficult as it can be to change and adjust rules and expectations that have been in place long before two families became one, in the long run it will be easier for everyone if there is one set of rules and one standard of acceptable behavior for everyone. That means that if one adult says all toys have to be shared and the other adult says what's yours is yours and what's his is his, there may be problems. Discuss the situation with your spouse and come to an agreement about what you are relaying to the children in the household.
Be clear on what needs to be shared. For example, if a child has a favorite toy that goes everywhere with her, that doesn't need to be shared -- that is special, just for her. But regular toys, movies and games can be shared. In fact, point out to kids that one of the advantages to their situation is increasing their library of movies and games. If possible, buy a few new toys and other age appropriate items for kids that are a gift to all the children, to be shared. They may grasp this concept easier with new things than items that already belonged to one child or set of children and now belongs to everyone.
Pick your battles. Parents don't need to get involved in every situation involving their kids. Sometimes, it's best to let children work things out amongst themselves. As long as the children are close in age, no one is being bullied, and the arguing is not becoming violent, it can be helpful for kids to work out their own problems with sharing. Stepping back a little will also save a bit of sanity for stressed parents who just can't handle one more fight over whose turn it is to play with that red truck.