LOL! I had to google it a long time ago cuz I didn't know what it meant either. D=Dear, so (H)usband, (D)aughter, (S)on, (W)ife.
Then BF, GF for boyfriend/girlfriend.
Oh, then there's FH/FW=Future Husband/Future Wife.
Annie, I think BF sometimes means *ick head, too. It does in my house, anyway. 