Any time you act for a minor or a mentally incapable person in litigation, or in other legal matters, you will be appointing a litigation guardian. Next comes the tricky part, from a limitations perspective.
Acting for litigation guardians is fraught with peril. Suddenly, the incapacitated personal injury victim or minor, usually incapable of appreciating their legal rights, may have limitation period commencing against them. To start your appreciation of this issue, read my 2007 series of articles : civmar07web, civjun07web