Invoices with deposits needs to be more flexible

Im hoping we can figure out a way to accept additional payments due other than the “black and white” of deposit vs. paid in full. We need more than two options. I put together a big furniture order for a client so they could see the entire amount due as it all goes to one receiving center, so one shipping quote. I had the client pay the deposit but some of the vendors ship at different times. So now I am out of pocket for paying said vendor, delivery company etc… until the rest of the items come in which could even be next year. There has to be a way easily that the client can pay an additional amount due if I request it.