Pickup with "C" time signature

It would be great if one could make a pickup beat when using the "C" or the dashed "C" time signature.

At the moment you cannot choose these both time signatures in the "new partitura"-wizard, so if one chooses the 4/4 or 2/2 beat and a pickup of 1/8 (or whatever), and tries to put in a "C" time signature, MuseScore will interpret this as a time-change, and will transform the pickup beat into a complete bar (C/dashed C). I am using MuseScore 9.5.0 on Macintosh and also tried with r2811-0.9.6-beta2.

Simple solution: Ability to choose "C" or "dashed C" in the Wizzard.
Advanced solution: an option to change the time without changing the signature where ever in the score/or just change the signature without changing the time. Funny, when I drag the "C" to the 4/4, I have two possibilities to drop it down, one makes the whole bar colored, the other makes only the 4/4 red – however, there is no difference in the result.

(By the way, hello everybody, I'm new at the forum, and using MuseScore for only about 3 month. About me: I play the lute, theorbo, etc. and work as a accompagnist - basso continuo - in early music ensembles, opera, etc. I have about 15 years experience with various music notation programs on Macintosh and Windows, Finale, Sibelius, Capella, and of course the most important lute-tabulature/early-music-notation programs, "Fronimo", "Django" and "xTAB". I think MusicScore is a fantastic project, and would love to contribute, unfortunately I have no idea about coding, so I can only translate into German and give some input from the early-music-user-perspective.)