Bumping this as it seems like a common workflow problem, a setting I'm unaware of, or a shortcoming of the software.
I don't want to make 30 duplicates of the Tree on the timeline but if that's the only solution I'd like to know.
If you turn off auto-transition mode in the timeline, you can then create individual keyframes first for your start and end values, and then add transitions to each selected pair afterward. That should help you to achieve what you're trying to do.
Once you've done that, if you need to make an adjustment later without affecting the adjacent keyframe you can do so by placing the playhead over the keyframe, selecting the keyframe, and then adjusting the property.
Thank you. This is an improvement to how I was working. I found that if the adjacent keyframe was at the same co-ordinate the software attempts to guess what you're doing and copies the co-ordinates. In my case this isn't always the intended behaviour and it would be good to turn off any automation for fine grain control.