Lease changed without consent

My 3 friends and I, one who works for the realtor company, found a 4 person apartment and are in the process of signing the lease. We discovered that one of the friends could not live there because he had no co-signer. The 3 of us had signed the lease, but the 4th couldnt. When we went to request the deal be voided and we get the money back, we were told that was not possible and we needed to find a 4th roommate or forfeit our deposits. The person who did not have a co-signer seeked consultation of an attorney and his money was given back... BUT our friend who worked at the realtors office had found a person to replace him and without the consent of the rest of us, replaced him on the lease by simply whiting out his name on the lease and replacing it with the new persons. I had not agreed to this new person and want my money back. Is it legal for him to just replace someone without a new lease being signed? Does this void both leases and the deal overall?