Hi Linda,
The answer is "yes", you can force required fields, but the specifics of how one does this depends on whether you are maintaining the database using custom userforms or whether you are having the buyers enter the contract data directly into worksheet cells--or possibly even both. If you are using the userform approach, then it is simply a matter of checking all the input data controls (usually textboxes) to ensure that all the required data is there when the user clicks on the button that transfers the form's data to the worksheet.
If you are using the direct worksheet method, then you must use the worksheet's SelectionChange event to determine when the user has selected a cell in a different row from the previous selection, and if so check the precious row to make sure all the required data have been entered. If this is your situation, post that fact and I'll respond back with some sample code.
Damon