New condition type should be available only in profarma invoice not customer invoice document

Dear Team,

Currently we have requriment that for the sales order we need to create a new condition type and this new condition type should be available only in Proframa invoice not in the standard invoice, could you please help how can we make this.

I think we need to write a routine but we need to know where and which place we should writ a routine, please help us on this.

Thanks & Regards,

MK.