concubinage guilty or not?

OllWe wrote:Good day!
My friend had been to a short relationship to a man. They had sexual intercourse once. Upon knowing that he's already married, she broke up with him. Although he keeps on texting and calling her.

He already have a family with three sons and a daughter. Matagal na silang nagsasama ng asawa niya for let's say 20years, pero ang sabi niya, unregistered ang marriage nila since hindi niya raw pinarehistro sa NSO when they got married sa munisipyo.

Now,nabasa ng anak niya mga messages niya sa friend ko and told her that they're going to file a case against concubinage sa friend ko.

Can my friend personally ask NSO for a copy of her ex boyfriends' marriage certificate just to prove that he's saying the truth about his unregistered marriage?

Is my friend guilty against concubinage?
If yes, is destierro only her penalty?

Thanks a lot!