Leader of a Big Family Medal

I'm pretty sure it's just the 6 visible juniors + however many juniors they have (0+0+7+0)


Also 1000 is not that unreasonable... at each level you get double the amount.
2+4+8+16+...
With 9 layers full that's 1022. So you just need to invite people 5 levels lower and you could do it by about level 45. Of course that depends on everybody getting juniors. But give it some time and I'd expect this medal to be pretty easy for anyone in 4th job.