There are limited options and we need to leveeage this option on Default Gateway under "Routes"

I think there is a limitation in NSX if using a default gateway. The Option that i  think insted of using a default gateway you can have static routes. This however will require an NSX-V edge to be connected to more than one Uplink. Although static routes will still be based on the destination network only you have less control on where the source traffic gets routed