How to post deposits (for customers and vendors) while in history mode?

SUGGESTED

Hello,

I am in the process of entering historical transactions and have come to an impasse: What is the proper way to post pre-payments that clients have made towards open invoices and what is the proper way to post deposits we have paid our suppliers towards purchase orders that have not yet been fulfilled?

I have checked similar questions but they are really old (7 years plus since they were answered) and I am assuming Sage50 Premium has changed since then.

I am assuming that posting a negative amount would do the trick but want to make sure I am correct before i go ahead and do it. As mentioned before I am working on History Mode.

Many thanks,