How to Add new button on account object lookup ?

Hi Hariom,

Some options you can consider :

1. Look into creating Quick Actions (Chatter Publisher Actions) to create the records.
2. Replace all your pages with visualforce pages so you can create your own version of quick create (Don't do this! Terrible idea but I wanted at least 2 items)
   Quick actions are really your best bet but you can't do them from the lookup dialog window. But it would save them from having to leave the record they're viewing.

Thanks