Prepayments between entities

I have two Trust - one is trading and one is for payroll processing.

The trading Trust pays a weekly amount to the payroll Trust, which we have been coding to an account and at the end of the month, creating an invoice and then allocating the payments made throughout that month to the invoice.

What is the best way to record these prepayments in MYOB AccountRight for both Trusts - the giver and the receiver.

I hope this makes sense :) Thanks!