BigBevo

Each apartment will be different. Have you asked the apartment directly? I went through this recently and every apartment that I was looking at had clear information (and yes it varied between them)

Example from one apartment: "If you are an applicant who is starting a new job but who has not been paid, you may provide an offer letter within 1 month of the start date on company letterhead"

Another apartment: "If you have are not currently employed but will be starting a new job in the vicinity, you must provide proof of your future employment and income"

You can go ahead and file. Do NOT report any of your siblings information from the W2. This can play out a few different ways, but most likely your tax return will be processed without any modifications. Your balance due/refund will not be modified by the IRS. And you will not hear from the IRS regarding the error on the other W2 at all.

Your sibling will get a W2c from their company and it will show their correct SSN. The IRS will eventually get the W2 and W2c. Their systems should automatically "remove" any of your siblings W2 from your account. If it doesnt happen automatically, the IRS will send you a notice saying you didnt report some income. You can call them and explain what happened or write back to them. As a final resort, you can then send them the W2c as proof in a response letter. But I wouldnt proactively try to contact them about it as you may confuse them.