Hi Aniket Gode,
As you know, Data blending requires a primary data source and at least one secondary data source. When you designate a primary data source, it functions as the main table or main data source. Any subsequent data sources that you use on the sheet are treated as a secondary data source. Only columns from the secondary data source that have corresponding matches in the primary data source appear in the view.
I would advise you to read this article, if you didn't already: Blend Your Data
Please let us know if it helped with your issue!