How to source a custom field on sales orders only w/o showing on estimate form?

Hello,

we are using a custom checkbox transaction line field on our sales orders with option "Store Value: Yes", which is sourced from a corresponding custom field stored on the item record.

This works as expected when creating a new sales order and entering items. But when we convert estimates to sales orders, the custom field will be blank for all lines. That is because this field applies only to sales orders, so we are not showing it on the estimate form and it doesn't get sourced to the estimate.

Is there a good way to have the field sourced from the item record upon conversion from estimate to sales order, instead of copying the empty information from the estimate? If possible I'd like to avoid "brute-forcing" it through SuiteScript.