Partner Determination

Hello experts,

I am sending activity in through idoc in crm system,here it carries 2 partners with it.

Ultimately we call crm_order_maintain in idoc function module to store this activity,at this point the partner determination is getting called and it will add additional partner related to the transaction.So as a result activity will have more than two partners now.

So how can i skip this partner determination?

Can anybody tell at what point this determination happens?any function module or badi?

Thanks & Best Regards,

Nikhil