回複：回複：未婚夫妻簽證 不得嫁娶他人K1持有人3月內不結婚須出境

Immigration Law regarding K-1 visa never changed: one must marry the person who petitioned K-1 visa for him/her and marry within three months after the entry. If one fails to follow these two requirements, one will be deported and can never change the status in the US unless wait for amnesty. CIS is always very strict on K-1 visa.

So the report is correct: one with K-1 visa cannot marry to someone else who is not the petitioner of K-1 or he/she losses legal status and cannot change to any other immigration status (immigrant or nonimmigrant).