How to customize Sales Invoice (Items)

as an IT guy, in my current invoice software - which i want to replace by ERPNEXT -
i book service items, as well as hardware, for customers.
“on done” i generate a position for each time entry with custom text from a service task,
e.g. “Remote service PC-11, on 1.2.2024”, with times from task and hourly rate from customer.
hardware items go as well into this “pot”, e.g. “CAT5 cable, 3m”
(which i dont manage right now as products, because i order as needed).
in a weekly routine, i click those positions per customer and create an invoice (or more).
further, for abos like webhosting, i can easily generate such a “position” from a recurring item,
to have a position look like “webhosting example.com from 1.3.2024-1.3.2025”

how can i implement this flow into ERPNEXT - if possible.
i am failing in the first place because “sales invoice item” is write protected.
i tried to add custom description item there, independently from “product”.

any help appreciated!
tia

Hi. Yes, you can do it.
In the sales invoice items table you have to expand the row to see the rest of the fields. There you have 2 fields that are editable: “item name” and “description” that you can modify. Another option is not to select anything in the “item” field and enter the concept that you want to invoice in the “item name” field and that will be what you see on the invoice.
You can also use another doctype called Timesheet to record the hours and tasks worked for different customers and add them to the invoice in its corresponding table. Using Timesheet will help you a lot to record works, billing and tracking.
You also have another “Auto Repeat” doctype available to handle recurring billing.

https://docs.erpnext.com/docs/user/manual/en/timesheets
https://docs.erpnext.com/docs/user/manual/en/auto-repeat

Regards.