You may have noticed that Group Family will not work if set to create groups when illegal characters are contained in the referenced attribute’s value: /\[ ] :;|=,+*?<>'
The same is observed natively, but an option is presented allowing the replacement of illegal characters with underscore.
This is by design. An enhancement request (TF00674156) has been created detailing the feature: As an administrator, include option in the Group Family’s settings to replace the illegal characters with underscore.
Please refer to this article:
How-to: Automate population of virtual attribute based upon streetAddress for Group Family
The product team will evaluate the request and this feature may become available on a future release of the product.