How can I create a transaction line field using list : amortization template ? Like a standard field : amortization template/schedule

they way amortization templates are added to vendor bills is amortization templates are set on item records; then when you enter the item the associated amortization template pops up; or you can added it manually like in your pic

but i used the amortization template not on the sublist item but expense

not best practices, but you still can use them on expenses, have to select them manually.

I know, but I'm in a configuration where I'm developing a script that will use custom transaction lines, one of which must use the list of amortization templates. However when I create a custom transaction Line I can't find any amortization template in the list.

😞. perhaps a scripting issue around amort templates. with expenses you MUST select a template, i.e. no way to pre-select it like with items, hope that helps