1)
Why did Dasan and Aviram add "Gam Histarer"?
1.
Ramban (citing Ibn Ezra): They meant either that Moshe had dominated them in many different ways or that Aharon had dominated them as well.
2.
Ramban: What they meant was 'Is the major evil that you did to us, to let us die in the desert not sufficient, that you now even 1 want to dictate to us in this minor way, to make us appear before you - To be sure, your intention is to dominate and govern us!'
3.
Rashbam: Placing "Gam" at the beginning of the phrase, 2 it reads "Ki Gam Sistarer aleinu Histarer".
1
Ramban: "Gam" in this case is synonymous with 'Afilu' (even).
2
Rashbam: As in Sh'mos 12:32 and in Bamidbar 22:33.
