Quotes, invoices, and/or Purchase order combining

I work on muliple rooms for a client/project, as most designers do. For example, in my case, the client wants to see the quote for their kitchen, separate from their quote for their primary and/or secondary bathrooms, mudroom, laundry room etc, but I don’t necessarily want to invoice them separatley for each. The current way they have to pay for 6 or 7 invoices separately, but if I were able to combine it they would just need to pay for 1. Combining also comes into play when I have to order all the product, for instance, I am ordering plumbing from the same vendor at one time but they are spread across 6 invoices which makes it hard for both doing the purchase orders and the tracking of product. I may end of with 100 purchase orders for a project vs only needing 15-20 because of not being able to combine the invoices/quotes and I’m worried I will leave something out if there are 300 plus items being ordered. Let me know if there are any workarounds in the meantime because this is not very efficient right now. Thanks!