Programmatically changing Map chart Marker Layer X, Y columns based on a drop down selection

[David Wormuth]

I have an image of coronary artery anatomy. I have made a spreadsheet that has X, Y coordinates where I want to place a dot on the image to represent the location of a graph. This information is summed over many patients and the size of the dot represents number of times that area was grafted in the population.

My data comes as a series of columns, one value for each of Z number of graphs:

CABSiteDist01, CABSiteDist02, CABSiteDist03, etc

CABSiteDistXX has an integer 1 through 15 that represent the grafted vessel and Ive Added Columns to my datasheet that bind the CABSiteDist01 to the XY spreadsheet. Ive done this again for CABSiteDist02 but now get X(2), Y(2) as the coordinates for the second graft.

Ive created a text area drop down picker to let the user select which graft they want to see the map drawn with, but I cant seem to figure out how the change the Map Chart to use the newly selected data column and related X, Y locations. I can see how to change one variable, how do I change the other two based on one drop down choice. Ultimately, I want to show up to 10 graft locations.