Reducing horizontal space between instrument name and frame

I've added another piano instrument to my piano score, called "ossia", to represent the ossia stave. I use a second instrument rather than a third stave because this will automatically put the word ossia before the stave each time.

But I don't like the way this ends up changing the horizontal starting position of my score, which results in wasted space. See here:

What I want is to reduce the space between the instrument name (the word "ossia") and the stave. I cannot find the right setting. I am able to move the instrument name to the right, via Text Styles -> Instrument Name (short), by increasing the horizontal offset. But that does not move the start of the system to the left, and there is still wasted space. I need that horizontal space because I have a ton of notes in the bar later on.

I have attached an excerpt of the score. See also that the first system will move to the right a bit, even though there is no ossia stave there (that instrument is invisible when empty). I would love to know if there is a way for me to make each system start at the same vertical line.