That is a great question! There are a couple of reasons why your homeowner’s insurance company would ask for your sister’s renters policy. If your Sister filed a claim in conjunction with your Mom, your Mom’s company would want to assess what would be covered under the terms of that policy, and what they would be responsible for under theirs. They may also be trying to determine who is responsible for paying for the temporary housing costs, and for how long that coverage extends under each policy. They may also be trying to determine if some household items were listed under both policies, and filed as claims by both Mom and your sister. Neither wants to pay for something that the other will, if they don’t have to, you know? It’s a pretty standard practice for insurance companies to communicate between themselves as much is as legally permitted, so that they can make the proper determinations on who is obligated to pay for what, and that payments are not duplicated. I would not worry too much about it. Thank you for asking, and I’m glad that neither your Mom or Sister were hurt – that is more important than any of their things.