Zehal already decided to support Arcturus's ideas because she found them rather good. Not to mention, even though the House Alvix held a stake in Starlight Drive Yard Industries, the number of stocks that their Clan held wasn't really that much, considering the size of the House Alivx.
Her Clan had tons of branches because most of the Mercantile Clans in the known universe tended to be huge to handle the number of businesses and various endeavors that they were participating in.
Some, like the House Alvix, which belonged to the High-Level Civilizations or High-Level Star Nations, easily had thousands of members, all of whom worked in the various business ventures created by the House Alvix.
In the end, those shares were distributed among the branches of the House Alvix, and even though her branch, the Main Line of the House Alvix, held the most, it wasn't really that much in the great scheme of things.