Multiple Reference Lists in Bibliography of Single Paper

I need to set up a paper that has two sets of bibliographies, each with references intermixed, so the “section” fix that is reported on the help forum elsewhere is not applicable. The requirement is that there be regular references and then “Grade A” references. I know this is tough to explain, so let me show you an example of what a paragraph would look like.

This is my first sentence that ends in a regular reference.[1] This is my second sentence that ends in a regular reference.[2] Now is a sentence that ends with a Grade A reference and so the number starts over but with a letter also.[A1] Now is a third sentence.[3] Now another Grade A reference.[A2] Now another regular.[4]

…etc…

Then the bibliography output will be:

Grade A References
A1. Author, title, etc.
A2. Author, title, etc.

References

  1. Author, title, etc.
  2. Author, title, etc.
  3. Author, title, etc.

…And both bibliographies / all the references would be drawn from the same EndNote library. (Although I am happy to use two separate libraries if that helps.)

Is this possible or too complicated for Endnote to handle? (EndNote X7 on Windows 7 with MS-Word 2013)

If you wanted sequential numbering and just wanted the A cited references listed first (This would be using an additional custom field to sort the records), but not easily to have two lists numbered differently. 

The only way I could see to accomplish this, is to enter the A citations in square brackets and the conventionally (since there will be fewer).  Then just before submitting, make a copy of the document, Unlink the fields for the existing citations and bibliography. Then change the temporary delimiter (in the format bilbiography dialog) to square  and it will creat a new bibliography.  You will need to create a new output style where you put the A in front of the bibliography number (citation template),  and the “layout” of the bibliography settings.  Then move the A list to infront of the rest of your references in the bibliography.