What happened if I file I130 for my sister ad her son and later on she gets married?

The marriage of a beneficiary of an F-4 sibling petition has no effect upon the approvability of a petition. The marriage of course should be bona fide and not for purposes of merely assisting the other party in obtaining an immigrant visa. Due to the limitations of the Lawyers.com Forums, Alan Lee & Arthur Lee, Esqs.’ (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.