It was a great episode and a shame it was the only time Lucy was on Knots Landing. There were so many possibilities to go with Lucy never explored. Either have her come to Knots Landing from time to time or permanently. Especially after she married Mitch Cooper.
It was never stated on the show but I had always felt that JR brought Lucy to Southfork after Jock and/or Ellie told him that they wanted their then only grandchild there.