Advice? (possesion charge)

So, last night my friend and SWIM were hanging out in the parking lot of SWIM's house, rolling up a blunt. Out of nowhere an unmarked cop car pulls up behind them and proceeds to question SWIM and my friend, asking if there are illegal narcotics in the car or if we'd been doing any drugs. They notice blunt guts on the side of the car and SWIM and my friend both say there are no illegal substances in the car. They asked SWIM and my friend to get out of the car and ask if they can search the car; my friend says no, but since his driver door is open, he proceeds to look around anyways. He doesn't spot anything, but then comes back to my friend and asks once again if there are illegal substances in the car, to which he cracks and tells him that there is pot in the car. SWIM and my friend get charged with minor possesion and since SWIM is underage, my friend gets charged with contributing to the delinquency of a minor.

What should my friend and SWIM do?
SWIM made the suggestion that he should take the wrap and say it was all his pot, so my friend doesn't get marijuana and contributing charges. The other option is to say that it is my friend's and SWIM goes home free. The cops said that it didn't matter if it was SWIM's or not, because it was in my friend's car (that actually isn't registered in his name), but I seem to think a judge will say otherwise.

HELP FELLOW STONERS.

 

Yeah, I know, but they were both involved. Do you think SWIM should just let my friend take the whole wrap?

It was my friend who said there was, but regardless, Duh.

 

Yeah, thats why SWIM isn't posting and I am...