How this plan works?

Hey all crackberry peeps :D

My sister is planning on getting an Iphone for her upcoming birthday, but from what I heard there are 2 data plans? A regular one and a blackberr one correct?:confused:

Well since the iphone needs a data plan, and we'll probably be getting a family data plan will I be able to use all the features that uses data? Or will it only work with a blackberry data plan.

Getting 2 different ones is out of the question because my parents are paying since we are like 14.

Just want to know is when she gets the iphone and family data plan will it work for my berry? Like can I use BB messanger, and browse, and MEdianet.

Thanks in advance :p