There is a field to add a Preferred Surname in Student Manager. However, you can't search for this, nor does the Preferred Surname feature anywhere else in iSAMS e.g. on Registers?! It would be great if it could as we have some students with a Preferred Surname different from their Legal Surname.
This feature is currently being developed. If you would like to have the beta version in the meantime, I can arrange for it to be added to your school.