Cenvatable excisable invoice

A ( Excise registerd Trader) buys goods from B (Excise Registerd Manufacturer) by paying ED.

Now A sells to  C (Excise registred Trader) by Cenvatable Invoice and passes ED to C

Question

1. As a proof of ED paid to B what document to be submitted ?

- under dealer invoice, there are columns for details of "manufacturer and excise duty paid" filling of that column is enough by registered dealer. as its belived that registered dealer has furnished correct data.

2. Is it possible for A to hide his source of purchase ie B from C and if yes how?

 - No he can not hide the 100% data, however he can show details of duty paid per unit ( per MT) in place of %