Not sure this is worthy of an answer since it's more about English than Japanese, but it was too long for a comment.
I see your point but I think you may be overthinking it. Languages aren't always entirely logical. If you asked me who you should ask about places to stay and I simply replied "There are students who've had their family over, so ...", wouldn't you find that an odd and quite disconnected statement? If I said "there are other students who've had their family over, so...", as you say, it isn't entirely logical, but it has a better flow to it and I think it is a quite natural response.
Another way to think about it would be to add some emphasis to give "there are other students who have had there family over". In this case the "other" distinguishes two kinds of students: those that have and those that have not had family over.
You should probably also note that although my translations have used "other students", where "other" adjectively modifies "students", ほかにも is actually adverbially modifying いる. The literal translation would be students who've had their families over additionally exist. You could then ask "what do they exist in addition to?" Answer: they exist in addition to you, who has not had your family over.