Principal plays favoritism

I'm curious as to how a Principal could possibly play favorites - what can a Principal do, for a child or family, that would exhibit favoritism? Is this a private school? Our (public school) principal makes no decisions which would impact certain children over others. All their decisions and actions are at a school-wide level. Perhaps if you rephrase your question or add more details, the advice of the community might be able to target the issue. 

Hello, I'm sorry you're experiencing that. In what ways are your kids left behind? If it is subtle, like the principal greets those kids by name with enthusiasm but not yours, it might just be that those parents have taken time to get to know the principal and so he happens to know their kids names. In that case you could just make an effort to get to know the principal or help the school in some way (active PTA might be too much time commitment, but one-time volunteering for special event or attending a PTA meeting, or just introducing yourself and your kid and saying hi). If the favoritism is more pronounced, like your kids aren't getting selected for things, you might meet with the principal and ask why. But you will likely have better luck (and better outcomes for your kiddos) if you ask in a way that you are truly open to the answer, as it may not be what you think. Asking in an open minded way and sharing the way you have been feeling might create a nice conversation with the principal. If there is clear discrimination going on, and the principal is just defensive, then you could always take your concerns to the superintendent. But in that case be sure you have specific examples written down with the facts. 

I believe you, but I think there is very little you can do.  One single parent has no real power against a principal (unless an actual law or policy is being broken, such as discrimination against a particular religious group for example).