Paul,
In a case like this I would look towards chaining fact tables. I don't know the proper term, I'm not a warehouse expert, I just build 'em.
What it would look like is something like this:
(Existing Fact Tables) -> CustomerData with only attributes (Dimension) -> FactTable storing the calculated measures for date of measure taken.
You'd have to be careful about including only the most recent fact for each customer when treating it like a continuation of the dimension, but it will both allow you to monitor changes to the measures being delivered as well as separate out the concern of modifying attributes on a dimension when indeed your measures are mobile.
From there, you can have a discussion about 'better ways to achieve the same result' with your developers.
Never stop learning, even if it hurts. Ego bruises are practically mandatory as you learn unless you've never risked enough to make a mistake.
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