Can I pay each line with separate credit card

No. It all goes to the same account so it doesn't matter. Koodo won't know it's going to a speicif line. But with credit card payments I Beleive it automatically pays the amount owning on the account and you can't enter how much you want the credit card to be charged. 

@NadirVirjee - To top up on Dennis's reply, you can make multiple payments on an account but it's impossible for us to assign the payment to a specific number. 

You'll be able to look up your payment history within Self Serve so that both lines can keep track of the amounts you paid. 

Just remember that since we're not able to assign a payment to a specific line. If one person doesn't pay for their portion, both lines would end up getting suspended, regardless of who made the payments.

I was pretty sure you could input the amount you wanted to pay no with a credit card. Therefore you could proceed to pay 2 different amounts totalling the full amount.