Hello Craig Arnott,

You could check this odoo app for your needs :"https://apps.odoo.com/apps/modules/17.0/sh_sale_order_history" if this works for you buy it or you can also ask to have a adding the same feature for it.

If you're still seeking further assistance ask in this thread, I will respond as soon as possible. 

Thanks.

Thanks for the reply Andry. 

Really appreciated but that’s not what I’m after. i don’t want to select from a single previous order. I’d like to be able to select from the customers accumulated sales order history lines.  

Hope that makes sense.

Hi Craig,

I assume you are talking between

1. Duplicate Sale Order
2. 1. If you are talking about this, you can simply go to your previous sales order, click on the ⚙️, and click Duplicate. After that you can remove the lines that you don't want to have anymore.
3. Create Purchase Order from Sale Order
4. 1. If this is the case, you might need to set routing which is quite advance and might confusing for you that's new.

Hope this help, kindly vote up and mark as solved the issue if this helps.