Combining Johnston accidentals

I'm trying to use these Johnston accidentals from SMuFL (https://w3c.github.io/smufl/latest/tables/johnston-accidentals-just-int…).

The MuseScore Master Palette has all of the individual symbols (as shown in the first table at the link), but some of them, such as U+E2B3 "accidentalJohnstonSeven", are designed to be combined with other accidentals. In order to do this in MuseScore, I have to add multiple, separate accidental symbols and then carefully position them so that they are correctly combined, which is a lot of work.

Is there any way that I can add the combined forms, shown in the "Recommended ligatures" table at the link, as accidentals in their own right - perhaps through a plugin?