Repost this under design dilemma or in the landscape design forum and you should get several responses. Include a picture, otherwise people will be giving advice out of context.

I love ballerina indian hawthorne-good choice! The boxwood beauty natal plum is very hardy and a similar size to the ballerina hawthorne. You could stagger them and that would look beautiful. I often use boxwood beauties in this way. Be careful to buy the variety that stays small and has little to no thorns (do not get the tuttle). It may get a little frost damage on the tips if we get really cold but you just wait until we are out of danger and trim it off. Good luck!

Deana M. Chiavola Bella Fiore Landscape Design