Muns in a master-detail report from different data sources

[dxwallace]

Perhaps someone can  shed some light on this question for me.

Objective: To link data from separate reports via a certain member like a product type in a master detail relationship.

1. The manual states that a mun alias is created for created for members (assuming you have the option turned on to allow this)
2. In another example in the manual, they were saying that if you are linking members (as with a master-detail relationship) you must link with using the caption() function of the mun of the two members.
3. The question is, when you are linking from multiple data sources, can't you just use the alias for the two muns in question (which seems like it should be the same in spite of different data sources, and despite that the muns would be different),  and if that is true why are they saying you should use the caption() function to complete the link when you could use the alias?
4. Or am I even asking the right question, which a definite possibility.


Hope the question makes sense.