How do I change a marker type (e.g., circle to triangle) for a user selected section of a plot?

I am using the "selectdata" function from John D'Errico's MFE submission to grab specific data points from a graph (although this method isn't really important—what's important is that a subset of a plot is being selected). I need to have the programmatic ability to change the marker type of any user selected subset that is originally plotted together (see image). So for the example image below, I would grab the four right selected circles and change them to triangles.

I just used brush tool to highlight an example of the marker types I want to change since it's easier screengrab.

I've been looking for the past 2 days and haven't found anything anywhere on here or the undocumented Matlab pages so outlook is bleak, but I'm hopeful one of you geniuses can help me figure this out.

[Tyler Goodell]

Maybe this will make it a little bit easier...Is there any way to change the shape of a marker once it has already been plotted using scatter?