We have options to paste to a staff above or staff below which does what I’m asking except only in those specific circumstances.
The issue is that if you’re dealing with upbeats, the labour to paste a bar with an upbeat to another instrument is quite a lot - you’ve to click on an empty bar, switch note value a couple times, breaking the bar up until you have a quaver at the end, and then you can paste.
The reason you might not want to copy the entire bar in the original instrument is because the other instrument could be finishing a phrase that you don’t want to reenter (or is a tied note value with dynamic markings that you don’t want to redo).