Patricia Arquette was in *Medium *from 2005 - 2011.
Rosanna Arquette was in What About Brian? from 2006 - 2007.
Jeez, apparently the list of actors who aren’t siblings on two shows at the same time would be shorter.
And as a bonus, their sister-in-law Courteney Cox was in Dirt for part of this period too.
Don’t forget David Arquette, who seems to have been in a bunch of shit during that same time period
Anthony LaPaglia was the star of Without A Trace from 2002-2009.
During that time, his brother Jonathan was on The District (2001-2004), Windfall (2006), and Cold Case (2008-2010).
Jonathan didn’t have a major role on the latter two series, but he was one of the main characters during his time on The District.
While John Belushi was on Saturday Night Live (1975-79), brother James was appearing on two short-lived TV series, Who’s Watching the Kids (1978-79) and Working Stiffs (1979).
Lisa Vidal starred on The Division (2001-2004) while her sister Christina played the title role in a series called Taina (2001-2002).
Also, while i can’t be bothered checking the exact shows, i’m pretty sure that at least one other Baldwin brother has been a regular or semi-regular character on TV while Alec has been doing 30 Rock.
Daniel was on Celebrity Rehab.
William Baldwin was on Dirty Sexy Money