My oldest doesn't know how to play with others

My oldest daughter will be 6 on tuesday. She is terrible at playing with others. We have 3 kids, (almost) 6yo DD, (almost) 4yo DS and a 1 yo DD. Our oldest is terrible at playing with others. If she sees any of them having fun playing something she has to ask to play then change the game with her "rules" so it isn't fun for anyone or she plops herself in the middle of the game playing something she knows will distract the person having fun then changes the game so no one has fun. Its infuriating. She wants to be the only one having fun all the time. We have to listen to what she wants or play what she wants or she ruins it for everyone. She's in girls scouts and the troop leader doesn't know if she can take her out again as she isn't listening to instructions. Most of the time I can curb her behaviour but that's not the case for others. In the past she's expressed that she wants to be an only child. Clearly that's not possible, we love all of our kids including her and won't have it any other way. Is this a developmental thing or is this something we need to seek professional help for? When she is doing HW or something herself the rest of us can play together and have fun. We love her so much and want to teach her how to play with others. All help is appreciated. via /r/Parenting https://ift.tt/2oEs964