I don't think you are being selfish. Since neither you nor your sister are little and you both live at home, I think your concerns are quite valid. I would suggest you talk to your mother about these concerns. It is better that you, your family (and the potential groom) consider all of this beforehand. Out of all of your concerns, the one that I think is the most important to sort out is the one that relates to your sister. [edit: I do not mean to imply that you should oppose their marriage, only that you should talk to your mother about what is on your mind.]