Hi Paresh,
If you want to restrict the item from getting cleared through FP06, then you can customize the FM FKK_SAMPLE_TFK115 to check for the main\sub combination and remove them
Assign this FM in the clearing steps of the clearing variant that is assigned to the following SPRO node against clearing type 03
IMG-->Financial Accounting--->Contract Accounts Receivable and Payable-->Basic Functions--->Open Item Management-->Clearing Control-->Define Specifications for Clearing Types-->Define Defaults for Account Maintenance
Hope it helps...
Thanks,
Amlan