I think they could beat all 7 together. They're both around Cell Games Goku level to me which should be more than enough to get the job done against 7. Individually is harder to assess. They are obviously strong enough to one shot the Jrs individually, but I'm not sure how they'd fare against a combined attack. Maybe 4-5? If the Jrs land a successful combined attack from the get-go, maybe 0...
If Cell Junior Senior is present the duo get slaughtered.