One payment received for 5 different invoices (2 being a negative amount)

I have received one payment from a customer covering 5 different invoices. (Total of $1696.33)

I am unable to allocate these. The difficulty I am having is that 2 of the invoices is a negative balance and needs to be allocated as an overpayment.

Here are the figures

Invoice 1 -484.18

Invoice 2 805.40

Invoice 3 482.18

Invoice 4 -27.77 (This is a negaive payment as it was an overpayment for a different invoice than the ones above)

Invoice payment - also a negative payment of 47.66 (to a different invoice than the above)

Therefore the total amount received was $1696.33

When I try to allocate to each invoice, it won't let me as I can't put in a negative figure. I even tried putting the negative figures in as a return, but then the remaining amount didn't match up to what the bank feed reconciled. Any help would be appreciated.