My case was similar to yours.
We were also asked to send the similar list of documents, such as police certificates along with adhaar and voter’s ID card, Indian passports (expired and current) and/or OCI, PAN/Income Tax Card, as a proof of relationship despite the fact we submitted marriage and birth certificate. Furthermore, these are all non-existence documents as none of us, PA, dependent, spouse and co-signer, are or were Indian citizens. We immediately wrote them to guide us what we can do regarding submission of non-existence documents as well as what were the issues with the submitted certificates (we did this via webform and email, mentioned in the pdf letter, both). Within a couple of days, we received communication from there to "disregard" the letter that they sent earlier and asked to send only police certificates.