Scenario
An offset using the Single Offset Partial or Variable Offset Taper can establish the location of the offset element by specifying the station of the reference element. However, if the station of the reference element changes, the location of the offset element does not retain the location based upon the reference's station. The location of the offset element is based on the distance measured along the reference element even when the station is specified. What happens is that the offset element keeps its location based upon the distance from the origin of the reference element.

Why this can be a problem
If the location of the offset element is based on a station of the original location such as a station derived from a Right Of Way point on as-built plan, the point should not move when the reference element's stationing changes. That can happen by alignment adjustment or the insertion of an equation or modification of the reference element's stationing. If you have had to reproduce an alignment from 80-year old plans, you realize that the initial location of the alignment can change as it is compared against survey data. It is true that an offset element can retain its position if it snaps to a location on the reference or another element. However, when there is no other known point other than the station of the reference element, you cannot easily establish the offset's location. I know that event points can be created for the reference element, but that can be extremely tedious.

Proposal
Provide an option to lock the stationing of an offset element opposed to using the distance from the reference origin in the absence of any other known point. I realize that it can complicate the normal use of the offset command when the station is unimportant.