twitter-oauth | Tiny program to make the Authorization header | REST library

I am not a developer so I apologize in advance if my question is really basic. I've managed to successfully install this Google script Twitter API integration below and send tweets from a Google sheet (the code was offered here). I simply use =sendTweet(message) in a cell, replacing message with the cell reference of where i have the text for the tweet, for example =sendTweet(C6) and the new Tweet will contain the pre-prepared text in cell C6.

What i'm trying to do is to add to the script the option of sending a tweet in reply to another tweet. Reading on Twitter's API documentation, I understand that the in_reply_to_status_id parameter needs to pass the in_reply_to_status_id in the API call URL but that's as far as my understanding goes.

I don't know how to define this new tweet_id variable and how to get it to pass the in_reply_to_status_id=tweet_id string in the right place so it will function. The ideal would be to use the same formula but with the addition of tweet_id for the reply, as a second variable. For example =sendTweet(message, tweet_id).

Your help would be much appreciated 🙏