medieval ligature signs

Thanks for this amazing software. it's really easy to use and very practical.

I have quite a specific request: I study and transcribe medieval music and
wish to know how I could insert "ligature" signs. medieval ligatures are
groups of notes that were written together but don't have the same rythmical
meaning as modern ligatures. We use something that looks like a vertical
square bracket looking downwards. The sign actually doesn't have any musical
meaning: it's just a way for us to show that the notes were grouped in the
original score. Does any such thing exist in musescore or do you think it
could exist at some point? thanks a lot (i'm adding a transcription sample
by R. Picazos. It might give you a few other ideas)