My Sister Sponsored my Mum and me to be green card holders, but I am in F4 category, would it speed things up if my mum sponsored me to?

It may make sense for your mother even now to put in a petition for you. The F-1 category currently has a backlog of approximately 7 years and the F-2B category for sons and daughters over the age of 21 less than six years. I will assume that you were not born in the Philippines or Mexico, which have much longer backlogs. The F-4 category that you are in right now as the sibling of a US citizen is processing cases for final immigration that were filed by November 2006 for all of the world except for natives of India, Mexico and the Philippines which have longer backlogs. Assuming that you were not born in one of the three countries, you are likely at least six years away from being able to immigrate. So it makes sense for your mother to sponsor you at this time under the F-2B category even if it is difficult to know whether you will immigrate faster under that category than your present one. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (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.