Our league has a max average per team. One of a team's new bowlers this year had 2 different averages, one from the same house but a different league and the other was in a house in a different county. Our rules for the league just say to use their book average if they don't have one already.
What would be their book average? The highest of the two? One average has this team in violation of our cap and the other doesn't.
It would all depend on just what your rules say.
Most leagues when they say use highest book average,usually mean the local association book.
Though that has been changing since it became easier to check averages from other associations.
So unless they specified using national average or any USBC league something like that, the average from another association most likely wouldn't be used.
If it's in another county then it's most likely in a different assoc. so that maybe why it wasn't used.