Hay ,

Have Form (DAP) with fields:-

PA_Name (Lookup Field from Different Form)

Status  (Drop-down with values Current , Arc)

Other Fields

On Success of this Form i need:- 

if PA_Name is already existed in old records than status is equal to current in Current Record.

and Status changed to Arc for all the old records which have same PA_NAME Value.

How can i achieve this ? Thank u in Advance.