Integrate the text receiving by api call to IBM voice gateway

I have a API which gives a particular text when we make a request to it. I have already implemented that sending request and receiving response by node-red nodes(inject/ change/ http request)

I have already created an IBM voice gate way connecting IBM TTS, STT and assistance(formally conversation) services.

Now I want to connect the response coming from that API call to watson assistance. Is it possible?
If so could you please let me know how to do it?

Thank you.