Payments for a single invoice can be split between different payment types.
Log into your account
From the menu, choose Invoices
Locate and open the Invoice you want to apply a payment to
Click the Apply Payment Button at the top of the invoice
A window will appear from the side titled Apply Payment
Choose the Invoice
Enter the Payment Date and Amount
Choose Payment Type
Offline Payment methods you must collect manually
Add any relevant notes or upload attachments as necessary
Click the green Apply Payment button
Complete the above steps again to apply payment methods as needed, until remaining balance is 0.