I’m transcribing Franconian motets into modern notation, and I include handwritten incipits (a sample of the original notation) at the beginning of each transcription (I use forScore for this). I separate one measure by placing a Coda on m.2 and hiding the text. Then, in engrave mode, I remove the gap between m.1 and 2 so that the barline is flush with the m.2 bracket. I also have to erase the m.1 bracket in Preview.
Here are screenshots of what it looks like before and after I write the incipit:
It is possible to remove all brackets from the first system, add a bracket at the start of the second system, and create a bracket after the incipit with a vertical line and two instances of staff-attached text, one for each bracket end: