Starting point/hash

is there a possibility to start cracking a hash from a point that i can choose?
i think if i crack a hash the multiforcer starts each time from the same password and goes on right?
so for example he starts everytime with aaaa then aaab or something like that.
so is it possible to chosse for example zzbb as the beginning point?
that would be great because my multiforcer stops very often during a cracksession with lentgh8 and charsetupper-lower-numeric-symbol with a hashlist of 20k hashes.
i think if i crack a hash the multiforcer starts each time from the same password and goes on right?
so for example he starts everytime with aaaa then aaab or something like that.
so is it possible to chosse for example zzbb as the beginning point?
that would be great because my multiforcer stops very often during a cracksession with lentgh8 and charsetupper-lower-numeric-symbol with a hashlist of 20k hashes.