I recently met a Russian girl named Margarita–“but,” she said, “you can call me Rita, even though I can’t really pronounce that.” This naturally leads me to believe that she was called by some other name in Russia, and so I’m curious to know: what are the usual Russian diminutives of Margarita/other variations of Margaret?
“Masha” is what I recall from years ago.
You could try “Margosha.” Or, maybe “Margaritka.”