Add payments to invoices added through the SalesJournal?

I am using the .NET SDK (C#) to export invoices and payments of those invoices from my own database into Sage50.

I managed to create invoices (payment type = pay later) in the Sage50 db using the SalesJournal class.

I now need to add payments for those invoices, but could not figure out how to do it with the SDK. I looked around in the SalesJournal, it's not clear if this class allows me to do this as I could not find the methods in it to make it happen.

I looked in the classes of the SDK but could not find the one that handles payments...

I checked in the SDK examples, nothing there either.

Is it even possible to do it with the SDK?