@Simrin-- I don't think so. If someone doesn't know about a conspiracy to distribute drugs and join it knowingly, they cannot be charged with it. There has to be evidence of these two points.
I'm sure if people knew about it and agreed to work with them, they wouldn't admit it at first. But there is always evidence somewhere, in phone conversations, mails and so forth. If there is no evidence, they probably really didn't know about it. There are a lot of people used by conspirators like that.