Export the data in the child feature class as a table and build a relationship class between the parent feature class and the table.1. Open the attribute table of the feature class that must become a table in ArcMap. Click the table Options button > Export. Specify a name and export the data as a dBase table.2. Import the table back to the geodatabase by right-clicking the geodatabase connection in ArcCatalog > Import > Table (Single).3. Build a new relationship class between the feature class and the table and publish the feature as a new service.