Next week, I’m using my AA frequent flier miles to fly from the USA to St. Petersburg Russia. I’ll be flying AA’s OneWorld partner FinnAir for part of that journey. While this is one flight itinerary, I will fly AA from MIA to ORD to HEL & then Finn Air to LED on the next day (meaning I have to spend the night in Helsinki). When I redeemed my frequent flier miles for this flight, American Airlines told me the following:

1) Since my flight layover in Helsinki is over 24 hrs, I will need to pick up my bags from baggage claim at the HEL airport. I’ll re-check in my bags when I leave from HEL the next day.
2) On my flight I’m going to check-in two 50 lb. pieces of luggage. When I check-in at the MIA airport, I’ll pay American Airlines a fee for the 2nd piece of luggage. Since I’m already paying American Airlines at the airport in America, I don’t have to pay for the 2nd bag again when I re-check in my bags w/FinnAir in Helsinki.
3) Since American Airlines allows me to bring a rolled carry-on bag & backpack (or laptop bag), then FinnAir will as well.

Do you think what AA told me is true? I’m kinda afraid that when I re-check in my bags at the Helsinki airport they’re gonna charge me an arm and a leg for my bags. What are your experiences when you’ve flown 2 different airlines on OneWorld? FinnAir restricts carry-on bag weight to 17.5 lbs & AA doesn’t. Do you think FinnAir will charge me if my carry-on is more than 17.5 lbs?

By the way, I redeemed my miles for economy class flights.