I have a custom field('Marketing Lead Status pick list (A, B, C, D)') on Lead. When I am inserting lead from web Marketing Lead Status set to 'A' and when lead inserted manually Status needs to set 'B' and When Lead is converted to opportunity with status A, B, C Status field needs to update D, When Lead is converted to Opportunity with Status D; no needs to do any action.
Please suggest me to proceed on this. Thank You in advance. (Not sure we can use trigger code or workflow rule).