G54R Rental Management - Enter a diferent AN8 for field Invoice to than the AN8 on Customer field

I have a big issue, we need to enter different address numbers on the contract, looks like I can save the
contract 3 different AN8  but when I saved the contract the (invoice to) field takes the Customer AN8
number. 

Example:

On the header of the rental contract I need the following structure

Customer Number (AN8)=4008

Ship to=4007

Invoice to=4771

If I open the contract an update the invoice to is working fine.