To begin, find the Billing tab on your desired project. To split up a payment between different methods, you will be using the online and offline features.

For this example, we'll start with an offline payment for a proportion of the total amount due. 

Select Record offline payment and choose your desired method in the pop-up menu.

Enter the amount paid and select Save Payment Record.

You will then see that a portion of the total payment was made. We will now charge an online payment to complete another portion of the total payment due. Select Capture Payment. Enter the client's credit card information in the pop-up menu and select Process Payment.

After you may scroll down to the payment details and notice that portions of the payment were made through different methods. To charge the rest of the payment due, you may restart the process and even choose a different offline method (such as a check or other).