Once they are sentenced, they can file a notice of appeal and ask the Court of Appeals to consider the sufficiency of the evidence and the trial errors that you feel occurred. You should understand, however, that witness testimony, even that of drug addicts and paid informants is "real evidence."
This answer is provided for educational purposes only and is not intended as the practice of law in any jurisdiction in which I am not licensed. The answer does not constitute legal advice nor does it create an attorney-client relationship. The answer is based only on the information provided, and may be inaccurate in the context of additional facts that have not been provided. The questioner should be aware that I am only licensed to practice law in the state and federal courts of Minnesota. Accordingly, before taking any action or refraining from taking any action, the questioner should consult with an attorney licensed to practice in his or her jurisdiction.
We also recommend that the defendants should carefully consult about their appellate rights with their own criminal lawyers ASAP. Good luck.