There are some cases where a company need to track invoices and expenses as part of a bigger project. For example a big project that is partially invoiced during the whole development process, with an additional functionality that allows to track outsourced services too (as expenses).
This “Project” logic, would allow to somehow group several invoices and view them as totals.
I don’t thing that this is too difficult to implement and i would be glad to start with it.
I think that the expenses functionality is already implemented and planning to be included in InvoicePlane 1.5.
If anyone has similar needs or simply wants to put two cents in this, please be my guest!