I created a field in my child replica but when I used arcpy.SynchronizeChanges_management the field didn't come through with the rest of the data.
Synchronize will not check for new schema changes.
Check these:
How To: Update schema changes with replication
https://community.esri.com/groups/technical-support/blog/2016/01/26/simplify-your-life-working-with-...
Schema changes—ArcGIS Help | ArcGIS Desktop