Re: Players with relatives who play/played on tour
Lindsay Davenport and Rick Leach are brother/sister-in-laws.
Same with Todd Woodbridge and Nicole Bradtke (nee Provis) - in-laws.
Robert Seguso (top ATP doubles player) married Carling Bassett (Top 10 Canadian WTA player).
Sybille Nouix-Chateau (French WTA player) married Jean-Philippe Fleurian (ATP player).
Miroslava Vavrinec (Swiss WTA player) married Roger Federer (some pleb who plays on the ATP Tour).
Guillermo Perez-Roldan and Mariana Perez-Roldan were tennis-playing siblings.
Andrei Medvedev and Natalia Medvedeva were also tennis-playing siblings.
Tommy Haas and Sabine Haas were another pair of tennis-playing siblings.
Jennifer and Steven Capriati - he tried to make it on the ATP Tour, but didn't.
The Jensen brothers, Luke and Murphy, have a sister called Rebecca, who tried her hand at the WTA Tour.
Rochelle and Rachelle (?) Rosenfield of Australia were sisters.
Annabel and Ben Ellwood - brother/sister.
Renee and Todd Reid - brother/sister.
Alisa Ogorodova is the daughter of Oleg Ogorodov (ATP player).
Apologies if any of these have already been mentioned!