Hi kidrobot,
Actually, the application is not for me but for my daughter, her husband and little boy. My son-in-law is the principal applicant being a licensed Avionic Mechanic (listed in high demand job). This is the 2nd time that my brother has filed a nomination. First application was for my brother & family who arrived Winnipeg in December 2008 and after a year, my brother filed for my daughter and her family.
I have no idea if you and your sister can be nominated at the same time. I suggest you visit the website www2.immigratemanitoba.com and check the Frequently Asked Question. The answer to your query might be there.
If both of you are single and your sponsor can support you not only financially, but can also provide accommodation, I think it's possible. This is only my opinion.... you can be considered 1 family. Di ba sometimes application is for a family of 5 or 6. I know my brother's friend was able to get his brother & wife and 4 children. Hopefully, it's pwede.... You just try... if they don't accept, then submit only 1 nomination. There's a second time pa naman.
God Bless....