Golden gate solution for oracle DR

We need to build a golden gate environment that will work seamlessly with our primary and DR dataguard environment upon a DR failover/switchover event.
What is the best solution with the least amount of downtime to achieve this? Is there any oracle Document that can point us int he right direction to acheieve this?

This is our Database setup:

We have currently 4 databases.

Database A - Primary / Database - B - Physical Standby DR Database of A

Database - P - Goldengate replica1 of Primary Database A
Database - Q - Goldengate replica2 of Primary Database A

Now If Primary Database (A) were to failover or swithover to Standby DR database (B) how do we ensure both our Goldengate Replica1 (P) and Replica2 (Q) databases are