But the "assignment" of income earned by individuals and reported in their SSNs is an issue.
No matter where the checks are deposited, how can they avoid reporting Forms 1099-MISC in their own SSNs on their own Forms 1040 Schedules C or other appropriate schedules?
I guess they could then pay an administrative company to provide them administrative services, such as office space, a receptionist, office equipment, phone answering, etc. But, they might be shareholders but would not be providing services to that administrative company so wouldn't be employees or receive Forms W-2, right?
Have they worked with a lawyer in their state to form the corporation, write up an operating agreement, etc.? They need to have you and their lawyer and their banker and any other advisors work together with the shareholders.