Koodo doesn't have family plans where mulitple lines can be under one plan. However, Koodo does have Free Koodo Family calling which is free calling to each line within the same account.
You may be interested in Koodo Prepaid for your kids if their usage will not be as high as yours/average user. Koodo Prepaid starts off with base plans of $15/month and you can add talk and data boosters. These boosters do not expire and will roll over to each month as long as you keep paying your base plan. I believe if you don't pay your base plan/top up your account within 90 days, you will lose your boosters.