Question regarding players switching on a free throw

[grizwald]

Hello,

I'm new to this forum. I'm not an official, so I hope I'm not breaking any rules of etiquette by posting on here. I'm just a fan, parent and volunteer scorekeeper.

In my daughter's game this weekend with her AAU club there was a strange situation.

Team B is shooting the second of two free throws. Team A subs in their big center. Coach A tells this player to switch with the other player on the block, to block out a certain player. Team B then switches their two players on the lane. Team A switches again.... This switching continues until the official calls a delay of game on both teams, nullifying the upcoming second free throw and going to the possession arrow to award Team B the ball.

Was the official correct? Someone once told me that the offense had to set first. This is something I only vaguely remember and I have no idea where I heard it, so I was wondering if this official got the call right.