The account holder( Steve, lets say) 1st need to call Rogers to let them know that the other person (Julie) will take ownership of one of the line.
Then, Julie can call and transfer her line into her own account. There will be a credit check as in any other account you create and Julie will lose any bundle discount that was on the original account.(tough she might get new ones if she add other services as well)
Both will keep their phone number and phones/contract!