Hello Ben,
the chainages of the horizontal and vertical alignment need to match. That usually is no problem if you create the alignment from a string line. But it will become a problem if you change the start chainage in the horizontal alignment.
The HA editor will change the chainages of all following aligment points once you click into the next line.
But, unfortunately it isn't changing the VA accordingly. And changing the VA is painful if you have lots of definition points. Because the VA editor is not updating the following chainages, and there is no right click function either. That's probably because the HA elements are connected to each other and the VA elements don't need to. If there is a gap between the VA definitions the system is interpolating the elevations.
Best practise to change the chainages of a VA was for me so far to start from the back and change them by hand, one by one. At least you can use numerical operations (+-) in that field.
Chainage equation might also work, but I haven't really got a grip on how BC is doing it yet.
A right click option to increment all VA chainages by a certain value would be a good enhancement to the editor.