I have the strange situation in which I imported a Musix XML from Cubase. One instrument doesn’t enter until Bar 11. In Dorico, the score created too few bars before the instrument comes in, ie. it now it enters at Bar 6. That means this instrument is out of sync with all the others. How can I insert bars for just THAT instrument, so that it pushes the start of the instrument’s entrance from Bar 6 to Bar 11?
Oh well, rather than wait for an answer, I just went back to Cubase added some notes to the first bars of that instrument, and re-exported the XML. Then it imported back into Dorico with all the notes in the right place. I would be curious to know if it’s possible to add bars to one instrument and shift its notes that way, but for the moment, I found this workaround.
You can use the “Insert” mode when inputting notes. Then, choose a silence that fits an entire measure and enter 5 of these. The notes in that staff will advance 5 measures, as you want.
Albert.
Or you could select the whole music of this instrument, cut it and paste it at the right place !
Yep, another useful way. 
MusicXML files exported from Cubase can go awry if you have some staves hidden in the score editor: those hidden staves end up exported completely empty, without so much even as bar rests included, and Dorico somewhat understandably doesn’t quite know what to make of that. Provided you show all of the staves in the score editor before you export the MusicXML file, you should be able to avoid this problem.