Keep in mind that you may be taking a gamble if you're upgrading 2 people using 500 milers.

There's a chance that only 1 seat is available to upgrade using the 500 milers, and then one of you would be in coach while the other is in J.

OTOH, if there are 2 seats open in the inventory that the 15k per person each way + copay, then you wouldn't have to worry about having to possibly cross your fingers for only 1 upgrade or possibly 2 upgrades to clear at the gate.

So if you want certainty that you 2 will be both upgraded, then consider coughing up the miles and copay rather than chancing it with the 72 hour upgrade window using the 500 milers.