When a toddler gets together with other children, sharing is always an issue. Sharing is only possible when children can trust that if they let go of a possession, it will return. To part with these possessions is almost like giving up a piece of themselves. It is a declaration of himself as a separate being.
Young children can also be generous at times.
They can throw a ball back and forth or hand a distressed playmate a favorite toy for comfort. Playing simple games like rolling a ball back and forth help convey the idea of give and take. Keep your expectations realistic. Typically, the relationships between siblings has a lot of emotional meaning to parents. In turn, there are some inevitable pitfalls.