Marriage law

She can issue a legal notice in the largest circulated newspaper.

She can file the proposed divorce case on the grounds of cruelty, desertion and bigamy.

The summons can be sent to the last known address.

Once it is returned undelivered then you can take steps to serve the summons substituted service as per procedures of law 

Yes, first wife can file divorce petition against her husband on ground of desertion and cruelty. Summons to case may be sent to his last known address and if returned undelivered then she has to get the order from court to get published the summons in newspaper.

Yes, in the first instance, summons could be served to the last known address and , if necessary, seek directions from the court for substituted service.

Very well analysed, opined and advised by experts, file petition in last resided  or known address against such husband, let the Court issue summons. When summons are returned "unserved" get it served by substituted mode of publication in newspapers with the permission of concerned Court, thorugh your lawyer.

If summons published in daily local newspaper but afterwards also husband not appeared then the court has power to grant ex parte divorce ?