Dynamic Forms in Word 2007

I need help in creating a dynamic form/contract where a sales rep can select from a number of plans (approx) and then based on those selections populate 5-6 fields for each selected plans (4-5) onto the word document. This needs to be protected so sales can’t change the numbers on the contracts. I havent had luck doing a merge scenario and am thinking it may be a combination of macros and merge. Any ideas??