Ah, I did think of a trick that would almost certainly not be in the help pages for PlotMarker.
Instead of thinking of 3 lists of n points, what if somehow you could turn your data into n lists of 3 points? And you use a PlotMarker of 1 for the first of those lists, 2 for the second of those lists, etc?
You have three lists of four points.
And now you have four lists of three points.
Use Plot on that with 1,2,3,4 for PlotMarkers and the first point of each of your old lists should get a .
Much simpler than before.
There are almost always a dozen different ways of doing anything in Mathematica and sometimes one of those is much simpler, if you can just think of it.