Does it mean you need the same invoice number in the split invoices? In most of the cases invoice stands for a single value. People have there terms defined says 30% percent advance and rest 70% upon completion In there Quotes. Here they issue 2 invoices, 1st for 30% and 2nd for 70%.
I am sorry I dint understand your need here.
looking at the logic for your Invoice creation, it will only be possible to Create such method through a custom action in quotes that will divide Quotes Total amount into those Percentages and save for the Customer and relate it to Quote to display under subpanel. The main issue is that if line items are required in each Invoice then it might need more thinking on how to handle those line items.