A couple of questions related to form customisation that may be useful to others, or there might be someone who's done this before:

Some of our customers raise a large purchase order in their own finance systems to cover all they expect to spend with us each year, with the plan that any in-year upgrades can just be billed against that existing PO, rather than needing a new order to be raised by the client. This works nicely for those of our clients who have lengthy / complicated spend-approval processes, but want to be able to get small extra bits from us quickly. We want to store the remaining value of these "Call Off Purchase Orders" so we know what's left.

I’m experimenting with the use of the “Customer Order” transaction document for this, as we're not using it otherwise. I’ve got invoices linked to Customer Orders, and a set of report cells / report tables shown on the Customer Order view that show me the total of the linked invoices and so on. All works quite nicely, apart form a couple of tweaks that I an;t work out how to do:

a) Is there a way I can remove the default view of the “line items” pane on the Customer Orders? For this there wont be any separate in items on the order; it’ll just be the sum of the line items on the related invoices. [I can’t see how to remove that on the ‘main’ tab, nor how to hide the main tab and replace it with a substitute]

b) On some of the built-in layouts there’s “text notes” shown on the forms with instructions about what to do (like the note about totals being automatically recalculated on save, that’s shown on the Invoice object), so fixed text that’s the same on every form, not a editable text field or a read-only field. I can’t see how to add my own of those to give some on-screen instructions. Is that possible?

Thanks in advance.