Prosecutors charge drug conspiracies based upon the weight of drugs dealt by the entire conspiracy. That means that you are responsible for not only the drugs that you dealt, but also the drugs that everyone you are alleged to be involved with dealt. The legal standard is whether it was “reasonably foreseeable” to you that the amount charged was being dealt by members of your conspiracy. In other words, you can be charged with what you should have known was being dealt by others.
Prosecutors will try to attach you to as much drug weight as possible. You need a lawyer that will fight back and stop them from inflating your level of involvement.