Form Design Question

I mocked up an example to illustrate my question a bit

A user lands on this form which is purely an edit form. The initial data is populated via a dialog. So when a user is editing this data the part that is bothering me is half the form is saved via a button click and the other half is saved automatically. Both via ajax, but that doesn't really matter.

My concern is that users may think they have to hit save for the bottom half (lists) to be persisted. I'm not a huge fan of instructional text everywhere on forms. I'd rather things be visually intuitive. Am I over thinking this? Is there something I can do to make it more intuitive?

I'd suggest visually blocking out the upper form with a different background color that seta it apart from the rest.

P.s. I really like Mockups too.

Bear Bibeault wrote:I'd suggest visually blocking out the upper form with a different background color that seta it apart from the rest.

I read "blocking out" and I think disabled. You don't mean that, do you?

No, no. Just talking about putting a background color behind the "subform" to make it appear visually separated from the rest of the form.