YOU SAID:

My brother I just heard my mum and stepdad having fun (if you know what I mean)

INTO JAPANESE

お母さんと継父が楽しんでるのを聞いたよ

BACK INTO ENGLISH

I heard your mother and stepfather enjoying themselves.

INTO JAPANESE

あなたの母親と継父が楽しんでるのを聞いたわ

BACK INTO ENGLISH

I heard your mother and stepfather enjoying themselves.