Reduce space between ONLY two staves for OSSIA effect

I read somebody stating that musescore doesn't support ossia staves. Ok, so be it.

An ossia staff is a little staff for localized variation of a part of a music, or a "third" hand like Albeniz liked to write on pieces like Almeria.

A "good" workaround [I don't like workarounds] to make ossia staves is to make a new instrument and hide empty staves + hide not needed beats**...
eventually set it to "small staff" - if you want: that's not the point to have it small.

The point is: this new staff is too far from the "parent" one, I need to move it close to the first one without changing the general style of the entire sheet, which is currently perfect, with multiple other staves. See attachement (image) to see all the issue I'm fighting over!

- Anyone can help me?
- Is there a planned feature OSSIA STAFF for future musescore release (3 :) )?

** (battute: non so some si traduce in inglese***)
*** measure - thank you Shoici