I have a customer payment of 150000 €, which pays the following invoices:
Invoice 1: €75000 paid €75000
Invoice 2: €25000 paid €25000
Credit note: 10000 €.
Invoice 3: 120000 € partial payment 60000 €.
What is the procedure for posting it?
You should create a line for the total amount linnked to the receivable account and the party. This will decrese the party amount to pay.
Then you can try to reconcile the payment line with the invoice lines.
If it is not possible to reconcile them you can split the receivable lines to allow reconciliation and link the missing one with the invoice 3.