The wiki says that you can share a planet location with your legion and said planet will no longer be in their planet list after 12 hours unless colonized or attacked. Does this mean if I share an unoccupied planet, and another legion member colonizes it that the planet will be permanently added to all other legion member's planet lists, thereby making it more difficult for everyone else to find new planets? Or will it only be on the scan lists of the person that colonized it and the person that originally held the planet location?

if you share a planet, it is only temporarily visible to other legionmates, unless one of them colonizes/invades it... then it becomes permanant on their list

the temporary shares do not affect scanning chance... but the permanant listing after a colonization or invasion will affect scanning chance

Cool. Thanks for the info, as usual, Lone.Lycan.