How does one add a chart to a Keynote theme

I have been studying how to create Keynote themes. I have been able to learn how to do a lot but I have not been able to figure out how to add a chart to a master slide.

I am not sure if this is possible.

I have found a chart in a deck I have and would like to add it to a slide master. I see some of the commercial themes have charts as part of the theme master slide set.

I cannot figure out how to add this chart as an "object" on a master so I do not have to go through the steps each time I want to use the formating attributes.

Related: on the Inspector Menu for Master Slides there is a check box for Object Placeholder. What is that for?

Rob