Digging up an old thread. If we want to fly J ideally on redemption (adult + <2yo infant), do both of us need to book Y, then upgrade, or can adult book straight to J on redemption, and infant cash Y booking then upgrade with points? Online you can not do infant only Y cash - but maybe you can the phone. Thanks

Last time I just paid 10% cash fare for infant in J, but trying to see what makes more economic sense here.