Maybe the answer is "suck it up, the price of the ticket was good and you have to pay up" but I'm hoping the experts here will have some ideas.

The situation: flying this Dec-Jan from US to Lisbon, then a few days later on to Tel Aviv, then finally Tel Aviv - USA with a stopover in Lisbon. Our fare class is "Discount." The weight limit for carryons is 10kg/22lb; not gonna cut it for a 10-day trip. I am not (yet) a member of TAP Miles and Go but have United Silver status. Apparently each checked bag will cost us $238 -- that's real money! I am trying to figure out how to avoid this if possible, so here are some specific questions.

1. First of all, TAP's website says that checked baggage must be purchased on their website through the "Manage Bookings" page. I have my booking open but there is nowhere to pay for checked baggage. Am I missing something? Or maybe can you only do this shortly before the flight?

2. It looks like TAP used to have a status match program where I could leverage having Delta Gold into having TAP Miles & Go Gold. Am I correct that this no longer exists?

3. If I used the United status match program to bring myself up to Gold status on United, would that allow me a free checked bag or does it have to be TAP Miles & Go? If I had the status, would that allow all four members of my party a free checked bag, or only me?

4. Can I use United MileagePlus miles to pay the baggage fees? Is this a good idea? (I don't necessarily mind getting a bad "rate" on the miles.)

5. Or can I / should I use MileagePlus miles to upgrade one or more of the tickets? (Maybe this isn't possible starting from the Discount fare?)

6. What am I not thinking of?

Thanks for all help!