Live-in partner of a minor may be held criminally liable

Dear PAO,

My brother started working for a non-governmental organization a few months ago, and he has been assigned to work in a far-flung area. He said that he has encountered two girls, both minors, who are cohabiting with middle-aged men. He and his workmates are really concerned and wanted to help these girls, but the nature of their work as well as their organization is very different, more for agriculture; so, they have very limited resources. So I tried to research the situation of these girls, and I came across an article about child marriage that mentions a law, RA 11596, which prohibits such a marriage. Since these two girls are not really married but are in a "live-in" relationship, can their respective partners still be held liable? Can a barangay official, social worker, or someone who wants to help these girls file the complaint?