my sister married a muslim guy under Special Marriage Act. After the marriage we came to know that the guy is already married to a muslim woman 5 years ago. the proof of the 1st marriage is a nikahnama. I do not know whether the nikahnama is registered or not.
1.Plz tell me whether my sisters marriage under Special Marriage Act still holds valid or does it now becomes void?
2.How and where can i check if the guy has already married someone or is lying?