I guess I have a hard time balancing survivability when I more than one person in the game with my MF. I am lvl 92 blizz sorc and can do Baal runs with full party no problem, but only because they come in to help at some point. I feel like if I am MFing on my own in a full party I will get wrecked.
sorcs are inherently glass cannons so on higher players you need to be dropping blizzards, teleporting to dodge missile attacks and shooting ice blast between blizzard cooldowns.
how much blizz damage do you do and how much life do you have? I could give you better advice if you listed your full gear, charms, and merc gear + aura type