That makes no sense. For extrasolar planetary systems where multiple planets share the same discovery date, those worlds are then named in order of distance from star, but they do not default the entire system on account of that. That would be madness. We were trying to put the Sol system in the same format that is used for exoplanets, and we can considered Mercury-Saturn, with the possible exception of Earth, to have the same discovery date. Following the same rules used to name exoplanets, those 6 planets would then be named in order of distance from the host star. Then planets discovered later are designated by order of discovery. It is absurd to try to rewrite the rules for one particular system for no concrete reason.