You are correct, importing will not allow the extra rows, and you can't "insert" rows into an existing form.

Assuming the import gives you the consolidated values you want from the proposal, you could

import from proposal, then copy and paste to excel and add the extra heading rows you want.

Delete/or don't save the import  in Sage, and then paste from excel back into Sage.  

Otherswise, if all the jobs will use the same format, set up one, without values, and then save it as a template (File save as template).  Then to create new jobs, load the template (File load template).

Thank you, Char.  We are in the implementation phase right now with a go live of Oct 1.  We are not using Proposals but the consultant represented that we either had to import from budgets or proposals; which I'm hearing is not the case.  Is there any benefit to using proposals for import?

Stricly a time saver/automation if you are using proposals.  

If not, you can manually create the schedule of values within the PB screen any way you want.

If you do them the same way all the time, then use the template feature.

Note:  In many of the menus there are multiple ways to do things to accommodate the many different ways companies want to automate their processes.