Confirm/Deny? Swap phone numbers SERO to other plan

[Meanee]

So I have been with Sprint since 2000. I wanted to get EVO but keep SERO. Figured I'd give SERO to my girlfriend, and keep EVO plan for myself. Now I called Sprint, who told me that I won't be able to swap phone numbers.

Did anyone recently try it? Take SERO number and put it on Everything Data, and take Everything Data phone number and put it on SERO?