Participatory KO is a new societal challenge for cultural heritage institutions. Through applying perspectives from studies of information infrastructures, participant's influence on a KO database schema is studied through discussions in an online user forum. Depending on the installed base of the institutional KO, participants' suggestion on modification of the schema are variously received and implemented. To meet the societal challenge of participatory KO, institutions have to be aware of what their installed base of KO is and how it can be flexible to and adjusted for user participation.