Usually restitution is ordered to be joint and several between Defendants, when there are multiple offenders, to ensure that the victim is fully reimbursed for their loss. The thought is that it is more equitable for a victim, who is usually deemed to be not responsible for what occurred, to be fully compensated for what occurred even if it means that a Defendant who is partially to blame pays in inequitable share. That being said, sometimes it is possible for your lawyer to speak with the prosecution, probation department, and the Court to limit your financial responsibility for what occurred. If there is already a judgment in place that calls for you to pay the full amount, you may have an uphill battle as it relates to ability to amend what you owe. You can hire a lawyer to help you, but there is no guarantee that he or she will be successful.
If you were found not guilty you should be under no obligation to pay restitution. You could be sued civilly and if found responsible have to pay. In general restitution orders as part of a sentence in a criminal case in Michigan are joint and several. This means that each defendant is responsible for the full amount; if only one person can pay than that person pays it all.