Add Dinamically Instances Of A Model In A Form

Hi I'm new using Yii and I'm having a problem, I have two models, modelA and modelB , modelB has a foreing key to modelA, so what I want is in the form of modelA add instances of modelB dinamically. I mean in the form of modelA fill all the fields of modelA and add 3 or 4 instances of modelB, then submit everithing together. There is any way to do it with yii?

Please an example would be helpful