Embedded views are great for displaying contextual data, in an almost relational way. There is a significant flaw (or is that feature?) to the way they work -- embedded views support "partial matches," and there is no way to turn it off.
Say, for example, you have a parts or products database. Each product has its own document (or page), and an embedded view shows marketing's comments on product campaigns.
Well, the old part number for a product is GOOD-1. And the new, improved version is GOOD-1A. Each has its own document, and separate marketing information.
Well, when you first create the GOOD-1A page, it will show embedded information for the old GOOD-1 product! That's because there are no matches for GOOD-1A (not for a day or two, right?) -- but there are matches for GOOD-1. GOOD-1 is a partial match for GOOD-1A.
How to fix this? Easy...
Go to the underlying view's design. Select the categorized column that is used for selection by the show-single-category function (in this case, the part number column). Change the formula for the column. Instead of "plain" PART_NUMBER, use the following formula:
PARENT_PART_NUMBER + "%FORCE PERFECT MATCH%"
Then, in your form, in the embedded view object, make the single category formula match:
MY_PART_NUMBER + "%FORCE PERFECT MATCH%"