Can you change a showname?

[proctor]

Never been asked this before but one of my liveries asked if it's possible to changer her horses show name as she simply doesn't like it. Can you do this and if so how? I'm guessing you have to send passport off maybe??

 

[FanyDuChamp]

It depends, I imagine. What has the horse won etc? I think there are issues with changing show names when the horse has won a lot. But not absolutely sure.
FDC