Student or Learner
"Which" can mean a noun, the whole sentence, or a phrase, so in the following, I think who or which both can make sense. If you use which, it can mean you like the fact or the situation of being with the same group as Janice, doesn't it?
Is "who" the only possible answer?
ex)I was in the same group as Janice, who(which) I like a lot.