I have a key-signature half-way a measure. I discovered clef change mid-measure, but not key-signatures. Is that possible?
There’s no straightforward way to do this, but there is a way that isn’t too hard. Use two measures, each with a time signature that is half of a measure. Check the box for a different display signature that matches the time signature you actually want. For example, if the piece is in 4/4, make two measures that are 2/4 but are set to display as if they were 4/4.
Now, put the key change in the second measure. You can then choose either to make the right bar line of the first half-measure into a dashed bar line (my recommendation) or make it completely invisible. A similar trick can be used for lots of unconventional mid measure stuff.
There may be a few adjustments you’ll have to make. Bear in mind that Finale will always consider this measure to be two measures, so you’ll need to adjust measure numbers after it (this is easy, just uncheck the box in the measure properties for the second measure that includes it in the numbering), and you might need to force or unforce some accidentals in the second half measure. You’ll also probably have to be careful about any line breaks in the score and parts, since you probably don’t want the two half-measures to be separated from each other.