RADNOR >> Hundreds of friends and family members filled the Radnor High School auditorium Tuesday afternoon for a memorial service for Sean Schellenger, the 37-year-old real estate developer who was stabbed to death July 12 in a street altercation near Rittenhouse Square.During the hour-plus service, several family, business partners and friends offered kind remembrances of Schellenger, a former star athlete at both Coatesville High and Penn State University.