Manish,
This is a great question, and the way CoreMetrics handles triggering the Manual Impression Tags, makes this process very custom. I would reach out to your Account Manager and they'll make sure to get the correct implementation done for you.
Here is a quick breakdown of the ways to accomplish this:
Option A
This requires an update to the CoreMetrics template to accomplish it through Tealium. With this update you will need to map impression_page_id to the Impression ID and impression_cm_sp to the Impression cm_sp values in the mapping toolbox.
Once these two steps are complete you'll get the tid tag that contains multiple values, but all within the same tag as you mention.
However, with this method you will need to manually track clicks on all these links as well if you want to see how many people are clicking through your promotions. To track clicks you will need to trigger a utag.link function on click of the link and pass parameters for link ID and link href. Then you would map these parameters to the Manual Link Page Id and Manual Link href values in the mapping toolbox. The Manual Link href value needs to contain the appropriate "cm_re" or "cm_sp" query parameter for the link that was clicked.
Example:
utag.link({manual_imp_id : "someID", manual_link_href : "somedomain.com/somepage?cm_sp=contextualnav-_-bittybaby-_-seatedbabyandbook"})
Option B
The other method to accomplish this would be to add a new attribute to the anchor tag of the site promotions or real estate promotions. This would be coded directly into the page, or in some cases I've seen these be added via jQuery in a JavaScript code extension with Tealium. This new attribute would be called "manual_cm_re" OR "manual_cm_sp" like so:
href = "domain.com/static/abc.html" manual_cm_re="contextualnav--bittybaby-_-seatedbabyandbook"
The CoreMetrics library, eluminate.js, will scrub the page and look for the "manual_cm_re" and "manual_sp_re" values and trigger the impression tag automatically. Then when a user clicks on the link, again the Coremetrics library will handle populating the link tag as well. With this method there are not any mappings that are needed. The code lives on the page and the CM library takes care of the rest.