This button should be changed to add another purchase invoice, and forget the selection of purchase (set this up so you automatically add a purchase). This would make things one step quicker. You don't need the prior invoices numbers, dates amounts etc. (you don't normally want a copy)
Genuinely staggered at this situation... such an easy scriptable request to add another button - both commands exist plainly, simply join the insert and new to one click... and here we are 6 months in and nothing other than a cheerful "do it this way! It's not the same but that's all you are going to get!"Much as I appreciate the efforts in the copy function, it's utterly inappropriate for User request.
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