Unless I misunderstood the purpose of the ChildNeedsGuarantor system preference, I think the description is misleading. It currently states A child patron [doesn't need/must have] a guarantor when adding the patron. However, this is not limited to children. It affect patrons whose patron category is set to 'can be guarantee'. I'm not sure what the best formulation would be. Maybe something like When a patron category is set to 'can be guarantee', the guarantor is [mandatory / not mandatory].