How do I handle my friend disciplining my child?

[Kariann]

My friend and I have children that play together. Her boy is 3 1/2 and my daughter is 4. She has a different approach to parenting than I do. She is also, half my age and this is her only son. I have another daughter that is 12. She is constantly yelling at OUR children. She interferes with the kids when they argue or disagree. She constantly yells at them in the car to be quiet. But, what is really upsetting is that she feels it's ok to yell AT my child, even with me there. Sometimes, I don't agree with her butting in. I find it insulting. She never says anything to me, she just yells at my daughter. I don't always agree with her. She actually yelled and charged at my daughter b/c my daughter wouldn't give a toy back to her son. (Yes, my kid was wrong, but I was walking over to remedy the situation. I am not the type to scream at a playground). She yelled at my kid, snatched the toy from her hands and told her ,"my son won't play with you anymore....he doesn't like brats". I was appalled by this behavior. It not only made my daughter cry, but it upset me. She constantly yells at other people's kids (even w/ the parents there). And she complains verbally and online that people don't take responsibility for their children. At this point, I am scared to say anything. I have asked her to "lay off" my child. And told her it isn't fair to my kid. I am her parent. She has apologized to me and my child. But, now she's done it again. My daughter is not out of control. Yes, she talks back to me, and she gets punished for it. I try and interfere with her friends fights only if it's out of control, or there is hitting involved. Then I punish. I try not to yell. I find it ineffective and upsetting. She yells constantly. When we go to the pool or park she embarrasses me by yelling so much at her child. How do I talk with her about this issue without offending her.? I want her to stop parenting my child.Am I going to loose my friendship? Now, my daughter is resenting my friend and I don't want her to disrespect her. Can you give advise.