Multi-product lines are not invoiced since they are used only to group child orders. Actually, child lines are individually invoiced taking into account the invoicing data specified on them (payments, etc).
In order to invoice the child lines of a multi-product line just follow the standard procedure, that is:
1. Launch the Etere Money > Invoicing module,
2. Use either the manual or the automatic invoicing. The latter invoicing method is used for this example:
3. As shown above, there will be available for invoicing all child lines related to the scheduled master line.