Bob wallis
It depends what St. Margaret you are talking about. There are several.
There were a number of princesses that later became saints including St. Margaret of Scotland and St. Elizabeth of Hungary.
St. Margaret's Home was created in 1852.
The population of Tivetshall St Margaret is 266.
St Margaret's Hospital was created in 1893.
St. Margaret's Academy was created in 1992.
St Margaret's Road was created in 1879.
The population of Stratton St Margaret is 21,366.
Margaret St. Clair was born in 1911.
Since both Margaret & Anne are Saints' names, then you can most likely choose these both for your Confirmation name. I am not sure if whether or not there actually was a "St. Margaret Anne," but, both are the names of Saints in & of themselves.
St. Margaret Elementary School was created in 1990.
St. Margaret's Primary School was created in 1842.