How to simulate an artificial caret in a textarea?

What I am trying to do is something similar to how collaborative editor works. I want to allow two people to edit the same document. And for this I have to simulate an artificial caret. I can extract the other user's activity in term of addition and deletion at specified location in a textarea. I will then transmit the location, along with the action to the other document. There I need to carry out the required change at the sent coordinate. I have searched and found enough ways to set the caret location and insert or delete text at the current caret location, but the problem is that the caret of the document moves to the location at which I make the change. I don't want that, I want to have two carets, one each for the two users. Transmit their changes to each other documents and make the changes at their respective locations, while showing two different carets. I just need to know if there are certain libraries that I can use, or even if I have to make this on my own, then how and where do I start. I don't even know how a textarea is represented within a browser. How can I characterize locations within a textarea, if I know that then I save the locations in memory and make the changes based on the input received. I hope I make sense, thanks for any help.