I know of a similar situation....the LLC for processing payroll was done to take advantage of Amish employees with F4029s.   LLC members had  F4029s (SSExempt approval for Religious reasons) thereby any employees with the approved F4029s did not have SS/Medicare w/held.    The LLC then charged the SCorp for leased employees.   Saved the SCorp lots of payroll taxes.

BTW -  don't forget to file that LLC return.