"...can't change the parent account..."
QBs probably is not letting you change it because there are Sub Accounts. May one for each of your Employees?
Create a new Other Income Account, then go edit the Sub Accounts and move them to be under the new Other Income Account. NOTE: QBs probably will not let you do it in one step. You may first need to make the Sub Acct not a Sub, but it's own account. Then go make it an Other Income and a Sub of the new Acct you created.
And since the Franchise told you to do this, I'm assuming they do not look ALL Income accounts - which will show up on the Reports. And I'm guessing they take their fee on gross not net, so the Expense of the mileage is not considered? (Hopefully Gross less tax & tips!)
If they do look at all Income Accts, then the only other option is to consider it a Liability Acct and that you're reimbursing your employees. But that may open a can of tax implications since you're charging your clients and paying your employees. You'd need to run that one by your Accountant.
