Hi @shelly-goel - as Manik mentioned, this code structure is not supported by Project Firefly.
You should consider modularizing your code in a way that commonly used functionalities should be available as (npm) libraries. They can then be used by different projects and apps. Npm libraries also allow you to manage the code releases with semantic versioning, so that there is no hard dependency for the client apps.
For the remaining pieces which vary by org / customer, they should be put in separate app code bases and deployed to the individual orgs, like what you have today.
This is the multi-tenant model that we are going towards.