As adults, we dont fight over who owns the microwave or sofa. We take turns or we use them together.
But to a child, toys are prized possessions. Especially for young children, toys are more than possessions (can be their sense of self). They use toys to explore the world and build relationship with it. “MINE” is probably one of the mostly commonly used word as they need to control what happens to their toys.
Our goals is of course for our children to be generous little people who learn to share and play in harmony. But parent guided “sharing” only interupts play and erodes parent-child relationship and teaches false generosity.
Do encourage self regulated turns during play. A child is free to use the toy for as long as he/she wants, so he/she can fully enjoys it, followed by giving it up to another child with an open heart. When he/she experiences the warm emotion that runs through his/her heart by giving someone something they want, and the child gets to see the happiness of the other party, they learn how good it feels to give. On the contrary, when we force kids to share, they walk away folding their arms feeling resentful. Also, we need to be mindful on coaching our children to wait for their turns.
Have a simple family agreement on sharing of property, it works!