Increased price for 7 adults vs 1 adult with I9 & O9
I'm looking at buying 7 adults tickets on TIA - LHR in June. Expert Flyer is showing I9 and O9, so looks fine to me to book in a single PRN for up to 9 people for either economy or business.
When I price for 1 adult I get fares (before taxes) of €29 (O HBO) and €139 (I), however when I price for 7 adults it comes up as €45 (O HBO) and €155 (I). Price jump seems to be at 5 people. I can't see anything in the fare rules on number of passengers which causes this price jump. Any idea what is going on here, or is this normal (I usually just book for 2 adults)