Embedding Existing Restful Api In Yii2 Restful Api

I want to embed an existing restful API (external source) in API, built on Yii 2.0.

Who met with such a task, tell me how to do better?

Create a standard controller and send requests through it or use yii\rest\ActiveController?

If it was versioned, you can still leave intact and make new api as next version.

Give your client sometime to migrate and eventually remove it!

I want to make external api a part of my.

I cannot change external api, only pass inquiries to it.

Please explain your problem in full!