OK, the term “barline joins” sounds funny; it conjures up the notion of getting into a queue for some intoxicating refreshment at the end of a long workday, not something having to do with music notation. (Though sometimes when working on your score all day, that’s exactly what you need!)
“Barline joins” is what Sibelius calls grouping two or more similar instruments in a system by connecting their barlines. When you set up a score from scratch or from a template, Sibelius automatically does this for instrument families, grouping the winds together, and likewise the brass, percussion, and strings, as such:
This looks quite normal for an orchestral score, helping the eye easily distinguish among the instrument families. However, if you set up a woodwind quintet from the default template, it looks a little strange:
This happens because Sibelius places the horn between the clarinet and bassoon — traditional in a woodwind quintet score, but not in an orchestral score. Because the horn is part of the brass family, Sibelius separates the barlines. We can debate the merits of the horn’s inclusion in a woodwind quintet later (maybe over that aforementioned refreshment), but for now we’ll want to connect the barlines together.
To do that, click on the bottom of any barline on the clarinet staff. If you’ve clicked correctly, you’ll see a purple handle appear. I’ve circled it here:
Now, just drag the handle down to the bassoon staff. This joins all the barlines together:
Of course, you’ll find that you can drag the handle up as well to separate the barlines; you can also click on the top of a barline and reorganize the way staves are joined that way as well. You should be able to join or separate staves in any combination you like — notably for vocal staves, whose barlines are typically not joined to each other in order to allow for lyrics to be clearly read.
What happens if you find yourself with a staff that has no barlines at all? This can happen if you’ve selected a barline handle and accidentally pressed Delete.
Fortunately, the solution is the same: click on the top or bottom of a barline on an adjacent staff, and drag the handle up or down so that the barline reappears.
If you find yourself without barlines on any staff whatsoever and need to restore them, temporarily add a new instrument to your score by going to Home > Instruments > Add or Remove, or just press I. Add any instrument to your score:
Then click and drag the barline across the staves. You can then delete your temporary instrument by triple-clicking within the staff and pressing Delete, or by removing it through the Home > Instruments > Add or Remove dialog.
And with that, it’s time to join the bar line!