Assuming that the lineage of an equine makes it eligible to join a Breed Society, you may still choose an ID only passport. There is no legal reason to register with a Breed Society. 

However, by registering with the applicable Breed Society, an equine can be entered into the society’s studbook register (subject to proven parentage), can be graded for breeding purposes, and receive a number of other benefits that vary from society to society. 

What do I do if my equine has more than one passport?
​

 © Equine Register® Limited 2018. All rights reserved.
​
This information is provided by Equine Register for the purposes of basic information sharing and guidance. However, any information provided cannot and must not be relied upon and independent opinion should be sought.
​