I just received this message (below) from someone Legacy (I had sent them same message as the one here). I tried this and it actually works.
This General Notes problem has been reported by others. It is logged in our bug tracking system as issue 5481: "Legacy 8 - Family Group Record Options for General Notes don't work correctly." The work around is to check mark all three Notes options General, Search and Medical. When all three are check marked then the children's General Notes will print.