Eastern society at horse show at Southampton, NY

The transcript covers the 9th annual riding and Hunt Club show, highlighting key participants like Constance Roberts in the hurdles competition. It describes the blue ribbon audience and introduces Bobby Dobson and his sister Jacqueline. The Herbert Girls from Southampton, Joyce and Joel, are also mentioned as part of the juvenile society sister team.

What is the name of the sister team mentioned in the text?

What is the relationship between Joyce and Joel?