If the person s article has a source copy it here Maybe someone will edit that article and remove both the claim and source and now your claim here is no longer verifiable If the other article doesn t have a source find one and add it to both articles If you can t find a source remove the claim from both articles There s no hard and fast rule about whether someone deserves to be included in a list of famous alumni Certainly you don t want every Joe Blow who graduates on your list A good start might be WP BIO which has criteria for establishing a person s notability to determine if they merit an article