Hello @Katare, Ashish - Ideally, you'll want to stay on the Premium tier of APIM (only 1 service instance) where the Azure way is an architecture that only deploys the Gateway component throughout the regions you specify whilst also providing you with the centralized/common components for Dev Portal, Management tasks, etc...
However, based on our conversation in your previous post, it seems that you are proceeding to implement 3 separate service APIM instances on the Basic tier, and are continuing to explore ways to merge duplicative components like the Dev Portal? I would caution you against doing that as it raises more questions & is not future-proof. If the end goal is to drive down cost from the Premium tier, I would look into self-hosted gateways & self-hosted Dev Portal configurations and then do a cost comparison.