50G / simultaneous multiple scatter plots + intersection of linear regression lines

[fire_for_effect]

I have a 50g and really like it. I like the RPN and all of the functions seem to be pretty powerful. I only got it recently, but I've been using different kinds of graphing calculators for about 20 years now.

I have a real specific problem with scatter plots and linear regression lines.

First, I've been looking over the manual and the internet trying to figure out how to graph multiple scatter plots at the same time, but it seems like you can only do Columns 1 and 2 or Columns 1 and 3, etc., from Edat (greek letter), you can't do all three columns at once IF Column 1 represents X and 2 and 3 represent Y-values. Or columns 1 & 2 as one set, and 3 & 4 as a second set.

Further, because it doesn't seem to be able to do this, I can't get it to find the intersection of these two lines. I can get the x-intercept and y-intercept just fine but I don't need that. What I can do is do a linear regression on both sets of data to get an equation for a line, put it into an array, and use the solver on it, that does indeed work. But that's a whole lot of extra keypresses just to get an ordered pair. I have experience on TI and Casio calculators and they don't have this seeming limitation. Any suggestions?