Adding A One-Off Charge To A Service Invoice, Possible?

[jjsararas]

I have a service running each month and sending automatically to a customer. I did some one-off work and would like to invoice them. Can I somehow add this charge to their monthly invoice?

[Michael]

When they are invoiced, click edit and add the row, then save it or you can just create them an invoice and set it for a certain date.