California Marijuana Possession Question

My question involves criminal law for the state of: California

My friend and I were pulled over for a broken taillight and we admitted that we had weed in the car, and were both given possession citations. Now since it was way less than than one ounce (around 2 grams) my friend wants to say in court it was his, since I am on informal probation for petty theft already.

If he does this will they dismiss my citation? It was in his car, and he had a bunch of other illegal shit in the car they didnt even bother with. Since they didnt ask us anything after we had our rights read all the court will know is that we both were cited, but shouldnt they drop mine if when we go he says it was his?

Why would the police walk away from a confession?

Im not sure I follow what youre asking...
What Im saying is can we not go in and be like it was his weed, but we both got citations, so im not sure why I am here and not just him? shouldnt only he get the citation if it was just his weed?