Despite the fact taht it is possible to integrate a CDS entity with 2 different entities of BC like eg: Accounts with Customer or Vendor, the opposite is not possible within the extensibility provided by BC out of the box.
Just a simple example.
Imagine that you would like to integrate 2 different CDS entities with one BC entity. With different CDS entities just means different value in an enum within the same BC table like, for example:
a. entity CustomItem1 and entity CustomItem2 to BC Table Item
b. entity Full Time Employee entity and Contractor entity to BC Table Employee
and the list can grow higer.

In the standard documentation, in the section how to develop a custom integration, it uses a subscription to OnGetCDSTableNo: https://docs.microsoft.com/en-us/dynamics365/business-central/dev-itpro/administration/administration-custom-cds-integration#enable-coupling-and-synchronization-between-worker-in--and-in-

This function is always returning the related CDSTable, but it is always a 1-1 mapping and in the signature there is no recordref or record pass through with the BC Table so that it is not possible to discriminate which CDS Entity has to be integrated with. Below the standard signature
local procedure OnGetCDSTableNo(BCTableNo: Integer; var CDSTableNo: Integer; var handled: Boolean)

With this IDEAS, we are requesting to test and implement all the needed events or CDS filtering in the maps, in order to allow the integration of multiple CDS entity into one single BC table using the extensibility framework provided out of the box