On each individual Invoice, after you have connected your Merchant Account, you will see an option titled Disable Partial Payments:

This setting will be toggled off by default (not checked off), allowing your clients to make a partial payment on the Invoice by using the 'other' option on the payment dialog, if they so choose:

By default, each Invoice will allow for partial payments using the 'other' option unless you disable it. If you toggle on Disable Partial Payments, the 'other' field will be removed from the payment dialog, requiring your client make their payment in full:

It will be up to you if you decide to accept partial payments on the Invoice 👍 💰