Question about adding standardized sentences to an input field

Hi all,

Quick question: I would like to create a letter generator with standardized sentences.
Is it possible to create a workflow or something that adds a standard sentence in a user-generated input field where the cursor is on the screen?

At this moment I have got the standard sentences in an option set. And I can add the sentence with a workflow to the input field. Only I cannot work out how to add the sentence to where the mouse cursor is standing.

Thanks a lot.