Indexing joined tables

I have a couple of tables from a SQL database that are joined to features (ArcGIS Server) in an mxd and published to a Map Service. I have indexed this service and all of the features are searchable except for the joined features. I join these tables instead of using the data link in Essentials because I need to symbolize on fields in the joined table. Is there a workaround to make this work?

Thanks!!