Multiple rows in a subform (Access 97)

Hi!
I have a mainform with a subform.
The subform is linked to a combobox(customerId) on the mainform. The subform is used to display orders from the customer selected in customerID.

How Do I set up the subfom so the defaultview is 5 rows. If customer A has orders 5 empty rows is displayed in the subfom and if customer B has 7 orders 5 is displayed and a scrollbar is added so you could watch the rest.

Sincerly
JAONHA