Multiple IDOCs based on multiple fields in File to IDOC mapping

Hello Experts,

     I have a requirement to create multiple IDOCs based on multiple fields.

     Earlier my requirement is to create IDOCs based on ShipID (i.e., for every ShipID new IDOC...I achieved this).

     But now the requirement was to create IDOC based on two more fields like

Source:

     ShipID1

     FieldA with value1 

     FieldB with value1

Target :

     1 IDOC to create

and If

Source:

     ShipID1

     FiledA with Value2

     FiledB with Value2

     ShipID1

     FiledA with Value1

     FiledB with Value2

Target:

     2 IDOCs based on FiledA

Like wise IDOC should create for every change in FiledA and FieldB.

If FiledA and FiledB has no changes then create IDOC based on ShipID

please help me in achieving this as this is an urgent requirement.