Frankly, I don't have experience with partner flights, but with credit from Herth, Thrifty, triprewards and others to Delta, BA and SWA. I got credits up to a year when I contacted Herth or Thrifty with airline FF number and my name saying they didn't post a credit for my rental/ stay with them etc. My FF number was many times created the same day or the day before I have contacted them about activity that happened few month ago. Credit appeared with SWa or Delta with the date of activity (even this account didn't existed then )