I wish, cupcake! But alas, that's not the way it works... she'd need another plan to get her own number. You can however get her a plan on your account and you can both call each other unlimited for free :) But of course she'd have to pay the $25 (or whatever plan she'd pick) as well.
Or, just lend her your phone or SIM card so she can finish the minutes for you :)
Sophia is absolutely right, Koodo currently does not offer family SHARE plans, i believe it has to do with how their billing is set up per line. It would be a great thing, but at least for now the unlimited calling between family members is there.