How to handle payment in advance from customers

Hello Forum, my sales process for new customers is via payment in advance, how should i process. Currently i am making the invoice from the sales order and receiving the payment there, but the customer wants a commercial invoice any time i ship partial, if shipped completely there is no problem i can just send the invoice but most of the time products arrive partially, how should i process this

I came across this guide in regards to ‘Resolving overpaid status’
Hope it helps.

That one does not work, since i dont have trouble keeping track of the payments, but of the delivery of the actual products, what would be the correct process to charge the value of a sales order in advance keeoing track of the invoiced items?

you recieve money in advance from customer right?
make a sales quote for all items
make a customer credits cotrol account and do the recipt in that
then any time you dispatch create a sales invoice and check mark delivery note

automaticlly for example 5 sales invoice connect to 1 sales quote and also after complete of all invoices your customer balance shows correct