MDX: Forming Complex "Structures" (for lack of a better term)

I'm trying to create a "structure" that contains (Customer, Date of First Purchase, Date of Last Purchase) where the last 2 items are members from the same dimension attribute. This structure will form the basis of some more complex logic...for example, I may have another "structure" containing (Customer, Date of Event1, Date of Event2) that needs to be intersected with the first:

Intersect(
   Struct1 (Customer, Date of First Purchase, Date of Last Purchase)
   Struct2 (Customer, Date of Event1, Date of Event1)
)

One option I'm considering (since a tuple cannot contain multiple members from the same dimension attribute according to this article) to create additional date dimensions with the same relationship to the fact tables and use LINKMEMBER.

Another option would be to create a set consisting of 2 tuples for each customer:

{
  (Customer A, Date of First Purchase),(Customer A, Date of Last Purchase),
  (Customer B, Date of First Purchase),(Customer B, Date of Last Purchase),
  ...
}

...and then using some FILTER/GENERATE logic to work through the remaining logic...but I'm not convinced this would be any easier than simply maintaining 2 separate sets:

{
  (Customer A, Date of First Purchase),
  (Customer B, Date of First Purchase),
  ...
}

{
  (Customer A, Date of Last Purchase),
  (Customer B, Date of Last Purchase),
  ...
}

Any suggestions/recommendations?
Is my approach way off?

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