Your easy child sounds like a really nice kid. However, the day will come when she will feel she has no friends, that nobody likes her, that everyone else has better friends etc. That's what MY easy child was like even though she also was one of the more popular kids (and one of the nicer kids, as well as being very moral).
I venture to say - your easy child is not responsible for how other kids feel. If she starts bending over backwards to make everyone else happy, she will be setting herself up for a lifetime of burying herself and her ambitions purely to make everyone else happy. While she shouldn't ride roughshod over other people's feelings, she also has to learn to be herself and to value herself.
Your easy child can say to other kids, "I'm playing with G today/for now. Maybe we can add you to the game? Or if we can't, then maybe you and I can play tomorrow. You are all my friends."
It is the other kids feeling insecure who will grumble and complain. If easy child tries to please them, she is giving them power over her. However, if she is kind to them but still makes a point of not excluding anyone, then although she may later on have times when she feels left out, she at least will know she can value herself for being a good person.
ALL kids should have the capability of playing on their own, or of reaching out to someone new or different. That is in theory - in practice, we tend to spend time with certain people over others, and feel a bit lost when our regular friends are not so available to us. But that is OUR responsibility, not our friends'.
It happens with adults, too. I think the adults who play the same sort of games are the ones who were not nice friends when they were children. mother in law & I were talking about this today - it is the funeral of an old friend tomorrow, a woman who was a good friend to many, who was kind-hearted and genuine. We expect the funeral to be crowded. And also attending - a woman who I think believes herself to be the current reigning queen of the village, the one who other women flock to and who always has the latest information (= "gossip"). mother in law is polite to this woman but is not part of the crowd that flocks to her. In fact, only a small group do so, and I suspect purely for the assumed social status of being part of the "in" crowd. THis woman is mean, a backstabber and a gossip. mother in law has her number and tends to avoid her without being obvious about it. I think this woman feels sorry for me because I'm disabled. Certainly she can be very condescending towards anyone with a disability (whereas the woman whose funeral is tomorrow - she would make a cup of tea and come and sit with you to talk about everything - natural, unaffected, genuinely friendly).
This is what these kids grow into. The little girls who are mean and spiteful CAN grow up to be decent people, or they may never learn anything (other than how to get their own way and control other people) and become like this woman, who I feel is in fact lonely, insecure and desperately needing to control the other women around her, using gossip and manipulation to get her own way.
easy child had a classmate who was like this woman - the little girl would tell the other girls, "easy child isn't my friend today. If you want to be my friend, you will not have anything to do with easy child."
So easy child would find herself alone at lunchtime at school, left to her own devices by her friends in their zeal to stay "in good" with the bully. The next day things might be different and the bully might be feeling generous, and invite easy child to play. The bully believed that she controlled the other girls completely, but she didn't - easy child would get phone calls from the other girls when they all got home form school. "I'm sorry I was mean to you today; A made me," to which easy child would reply (sounding like me), "And if A told you to jump off a cliff, would you do that, too?"
Looking back on all this from the distance of 15 years, easy child has wonderful people skills. The friends who managed to break away from the control of the mean girl have also found their feet professionally. One girl, more in thrall than the others but still trying to find how to do the right thing when she was younger, has found it hard to work out what SHE wants because for too long she has followed other people - the mean girl, other friends, boyfriends especially.
And the mean girl? She's as bright as easy child but has failed professionally because of her own insecurities. She can't stick at any one career path, because when the work gets difficult or the going gets hard and she tries to manipulate the situation, she can't control it and so chooses to drop out instead. She never had to work through the unpleasantness to find the good things on the other side (including her own self-reliance).
I feel sorry for this mean girl because I know a lot of her insecurity stemmed from getting almost zero attention in the home - she is the younger sibling of identical twins and people would always be saying, "Oh, aren't they cute?" or "How are the twins going?" as if there were no other children in the family.
Very sad. She tried to get the love and attention from her friends, to replace what she didn't get from home. She's been into drugs, under-age sex (and her parents STILL don't know) and is a very unhappy person.
Do not let your daughter grow into an unhappy person, someone who can't find that well-spring of strength deep inside. Now is the time she needs to learn about its existence, and to also learn how to be a good friend - to her friends as well as to herself.
She must do this by herself, but you can support her by listening to her, advising her and helping her to feel she is a good person.
If your daughter is already popular, then she clearly already has good qualities which will stand her in good stead. However, she will also be an early target for jealousy (as easy child was, from the mean girl - this is why she was mean to easy child, because easy child had what mean girl did not).
Keep your girl on the moral straight and narrow, give her the courage to do what is right even if it is not the popular thing to do. She must learn that you can't please everybody.
It IS much more difficult with girls, isn't it?
Marg