If you want two different already existing accounts under one bill, you should be able to link the two accounts as long as the other person gives you access to their account.
Since I see you mentioned yourself as a mother, I'm assuming you want your kid under your account, if this is the case you can simply add a 2nd line to your account for your kid and you will get one bill.
Not quite. I have the koodo bill under my name, and my son pays me. I wanted to know if he could set it up on his banking profile and then pay it directly, cutting me out as the middle-man, so to speak. I am not asking to have it switched, just augmented.