Workplace..

So I’m a foreman at a shop.. well I became privy to some information today where I learned that one of the guys (33) is sleeping with one of the girls (17) . I live in Canada and I’m just wondering wtf I’m supposed to do with this or do I leave it??? Ps her dad also works in the shop so I imagine if I heard about it, he will soon find out too . I’m just wondering what the proper, professional steps are to handle this ?