Yes. Once a civil lawsuit is underway, parties have the ability to compel other parties (even, sometimes, non-parties to the litigation) to answer questions, pr

Yes. Once a civil lawsuit is underway, parties have the ability to compel other parties (even, sometimes, non-parties to the litigation) to answer questions, produce documents, and do all kinds of other things they might not want to do. There are various justifications but none probably would appeal to you right now based on how annoying it is to get a letter like that. Rule 34 of the various states’ (or federal) Rules of Civil Procedure is a good place to start learning about this. Good luck, this sounds like an interesting situation.