In Detroit you just go to their website and set it up. They tell you which innings are available and you pick. They have a limited number per game so it doesn’t get old.
I’ve done it twice, once for my niece and my daughter’s birthday when they were adults. You can even pay for a visit from the mascot with autographed balls.
That was cool when the mascot showed up with signed balls. That could easily be an engagement ring and avoid getting tackled and arrested.
The other time our daughter had her bachelorette party at a ballgame, I paid for a message from her wedding party and arranged it but they picked the message.
It’s pretty cool.