Hey @abhijithr !
In the interest of ensuring that there is not another issue impacting the MCMID being fetched, have you been able to confirm that you're seeing it set properly in Adobe?
I've seen implementations set ECID as an eVar and set in a data element to ensure that there aren't instances where ECID isn't being set that can impact stitching data using Data Insertion API. Are you utilizing Launch to send to AA? If so, using the Adobe Experience Cloud ID Service Extension would allow you to set up a simple data element to make ECID available using "_satellite.getVar("<your data element name>").
See below screenshot:
![Screenshot 2024-06-20 at 11.04.58 AM.png Screenshot 2024-06-20 at 11.04.58 AM.png](https://experienceleaguecommunities.adobe.com/t5/image/serverpage/image-id/75923i60DE83AE0C4C3FE1/image-size/large?v=v2&px=999)
However, if for whatever reason, there ends up being issues that prevent stitching via the ECID (which probably makes the Data Insertion API not a great solution for your requirement of stitching data from backend to Adobe), the cartID COULD be used to capture in an eVar, and then you could upload a classification of the data you want to see in Adobe that is tied to the backend orders keyed off the cartID if that is available. https://experienceleague.adobe.com/en/docs/analytics/components/classifications/c-classifications for reference. This isn't the best solution, as you are limited to uploading off the cartID and if the value is not truly unique (i.e., could be re-used) it could result in problems in the future. But it could allow you to classify simple details such as "total order value", "# of products", etc.
Hopefully one of these two options help you move forward!
Thanks,
Andy