Update and insert forms?

Hi everyone!

I’ve been doing CRUD with the search, delete, update and list (grid) on screen and Insert in a modal.
Now, I have a long form and the modal window is not the best option… Should I create a form for insert and another one for update? For update, how to send the selected data (for example products) to another page? If using the same form for update and insert, how to know when the action is to update or to insert?

Sorry for so many question! Newbie here!

Best
Otavio