Hmm.. well, did toi try the Polyjuice potion yet? If toi did, then toi might be able to get into the common room par going through the chapter, like toi always do.. (I haven't been on Pottermore in forever so sorry if I get stuff wrong) If toi can't do that, then maybe , try and add somebody that's a Slytherin and see if toi can get in then. =/