hey all - i’ve created a custom list + entity field, “order source”, that I’d like to place within the “primary information” section of our sales order form - alas, I don’t seem to be able to figure this out on my own - is it possible to nest a custom field within the primary information tab of a record?

Yep. In the customization of the form, go to fields, move elements between tabs, and move it to main, the n apply the primary information field group

An entity field would be on the customer though. You need a transaction body custom field

you the man Kristofer! Thank you kindly