Allow customers to make partial payment for invoices

[RishiFSP]

@kernowlass 

@sharpiemarker 

@Nuada 

@Christine115 

@Sparky883 

I want to allow my customers to make a partial advance payment on an invoice. 70% is due immediately, the remaining 30% is due before shipment.

I can not find the "Allow partial payment" when I create an invoice.