In a similar case of mine regarding a core document, I filed an objection application to marking the xerox copy.
It is the duty of the complainant to prove his documents and wherever originals are reqd, he is bound to produce at time of filing his evidence itself. that. my application was accepted in trial court and now other side has gone for revision before the sessions court.
For ur arguments, let me know what citations u r referring to. Shobha Rani case is the most imp in this circumstances. u can take the stand that lacuna cannot be allowed to be filled up after the stage for the procedure is over.
let me know ur progress pl. we r both in same boat. All the best.