If I date a girls sister to get closer to her....?

If I was to date the sister of the girl I like, gain her parents approval and unconditional acceptance in to their family and woo the girl I'm dating so much that she brags to her little sister, could I in fact make her little sister jealous enough for her to break up with her boyfriend and date me instead (thus having me breaking up with the older sister I had no intention of dating seriously to begin with). That way I get what I want, and only the sister and other boyfriend loses... baring the fact the parents don't give a crap about the change in relationship).