Reimbursement of payroll costs from my sister company in QuickBooks

I have two related companies. The main one has several employees and handles payroll for employees through QuickBooks, while the other is much smaller and only has one employee. Since my smaller company doesn't have a QuickBooks account, I manage my only employee's payroll through my main company and then reimburse my main company for all the payroll costs. What is the best way to record the reimbursement from my sister company to the main one?