Grouping payment

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.

You mean divide the amount received to match the lines due and reconcile it like that?

Indeed the simple way is to not try to reconcile but just let the all the lines as-is.
This is not really a problem as Tryton supports to work globally on receivable. The dunning module will deduce the payment already received. The reconcile account wizard will try to find an exact reconciliation if possible other leave it as-is.
Now some does not like to work like that and wants to have more work by make exact matching. In the case of the example, the easiest it to group all the lines which will be reconciled and the remaining will be posted as delegated reconciliation.