My 3-year old Elijah is starting to like her cousin Svetlana ( 4 y/0). They always fight during their younger age and I guess it’s part of growing up. They now play and cooperate with each other. They may still fight at times but at least they know how to forgive and take turns when it comes to playing.
Elijah shows interest in any kind of Angry Birds toys, Svetlana also learned to love it so they play together. Time comes that they don’t share but they resolve it themselves. Elijah doesn’t have the chance to play with other kids yet. Svetlana on the other hand is very excited when it comes to friendship because she will approach the kid immediately even if it’s their first time to meet.
I let Elijah play outside every morning so he can meet those kids of his age going to school. In this case, he will learn to say HI, goodbye and eventually play with them.