What is the legitimate Islamic ruling on a marriage in which a girl other than the initially engaged one was presented, while there was a previous promise to another person to propose to the same girl, and should the suitor have been informed about the existence of this annulled promise?

There is no objection to a father offering his daughter, whom he deems suitable, to a suitor, even if the suitor came to propose to her sister. This is permissible on condition that the father specifies which of his daughters he is marrying to him, otherwise the contract is void. As for the father breaking a promise with a previous suitor, it does not affect the validity of your engagement and marriage, because it is considered blameworthy breaking of a promise if done without excuse, or if the previous suitor did not show up at the appointed time. The guardian is not obligated to inform the suitor about a previous promise. Furthermore, your engagement is not considered an engagement over your brother's engagement as long as the father nullified the previous engagement before you proposed.