This is based on https://github.com/musescore/harmonica_tablature
This fork adds the Tremolo Harmonica in addition to all the harmonicas supported by the original plugin.
The fork also offers the Tremolo Harmonica tablature in two variations: Tremolo Harmonica Classic and SMuFL
The difference is in the font type: whereas the classic one uses pretty standard letters, the SMuFL uses the figured bass font found in SMuFL.
Please note that the naming convention found here follows the Asian tradition, where instead of the hole number the solfege number is used.
(Although github user Doorbash has also added the tremolo in this fork musescore#7, his seems to follow the western tradition)