Build a new relationship to the orders where you use two global fields and the contact ID field to match a range of records. You will need to create a field within the orders that gives each record a unique serial number that can be matched to the global fields.
Contact - Add 2 global fields to store the range to match the portal. - zg.filterOrdersStart & zg.filterOrdersEnd
Orders - Add field that numbers each individual record for the a Contact (1 .. n) - contactOrderNumber
Build a relationship to Contact and Orders using both ContactID and contactOrderNumber:
contactID = contactID
zg.filterOrdersStart => contactOrderNumber
zg.filterOrdersEnd <= contactOrderNumber
Then populate the two zg.filterOrder*** fields and see that you only have the limited number of records. Then add buttons to move forward and back which increments or decrements the two global fields by 10.