Custom DPC update issue

We are using a custom DPC, and a few enterprise customers with critical use case. Because of their strict Change Management (CM) processes, they need at least 60 to 90 days to test and approve any app update.

Currently, we suggested to use Managed Google Play and Postpone policies, but there is a problem

Here is the exact problem workflow:

Day 1: Customer enrolls devices on V1 and applies a 90-day Postpone policy.
Next 90 Days: We release V2, V3, and V4 to production to support our other market customers.
Around Day 90: The customer’s IT team thoroughly tests and approves V3 from their Management.

Issue : The moment the 90-day postponement expires, Managed Google Play automatically pushes the highest available version(V4)

The customer wants V3 to be updated in all devices, but Managed Google Play forces them straight to V4.

Since our DPC is already live, we can't stop releasing updates for other Customers.

How can we solve this issue?