How to Import and Enable Third-Party Voices in Heygen by using APIs not from dashboard?

Hello Heygen community,

I am currently exploring the possibility of importing and enabling third-party voices in Heygen, similar to how it is managed within the Heygen dashboard. I noticed that the following APIs are being utilized in the dashboard, but they aren't mentioned in the official documentation:

https://api2.heygen.com/v1/third_party/voice.enable
https://api2.heygen.com/v1/third_party/play_ht/voice.list?key_id=KEY_ID
Can anyone guide me on how to integrate and enable third-party voices using these or other relevant APIs? I would like to manage this process from within my app using these APIs.

Your help would be greatly appreciated!
Thanks.