booking extra baggage on aer lingus through student universe

I’m trying to book a flight from Frankfurt to Chicago with Aer Lingus through Student Universe, and here’s the thing: the ticket comes with one 23 kg checked bag, but I really need to bring another suitcase. The problem is, Student Universe doesn’t give me any option to add extra baggage during booking. I even spent 15 minutes clicking through every possible button and link, hoping I missed something, but nope—nothing about extra bags. Now, I’m wondering if I can just go to the Aer Lingus website and add another bag there. But then I start worrying: will I need some special booking ID from Student Universe to even find my reservation on the Aer Lingus site? Or will the two systems not talk to each other, and I’ll end up stuck paying way more at the airport? I really want to avoid that last-minute airport fee shock. Has anyone else managed to buy extra baggage online for an Aer Lingus flight booked through Student Universe? Did you run into any issues with the booking reference numbers or anything weird like that? It feels like these third-party sites make things harder than they need to be, just when you think you’ve got a good deal. #travelquestions #aerlingus #studentuniverse #Travel