Can ID be used on multiple forms?

Can ID be used on multiple forms?

Since ID is unique for each record, I guess I can't set the ID of a record in another form, is that correct?

Since I have a record that's starting on one form, and transitioning to a separate form, in order to keep a link to the original record, I assume I must create a third id type field for the two records on the separate forms to share - is this correct thinking?

Thanks!

Kenny