There is no provision to "add" anything to your CHL.
You must use a .32 cal or larger to qualify; after that (subject to the revolver/semi exclusion referenced above..and your budget) you may carry whatever you can effectively conceal.
If you are in the DFW area and looking for a good CHL class/instructor, please pm me. I am not a CHL instuctor, nor do I have and any financial interest in his operation, but the one I go to is very good and reasonably priced.
PS--Clay types faster than I do.