Advice: alternative to providing tax returns for immigration visa interview

[longmarch]

I'm a sponsor of immigration visas for my brother and his family. I got the impression that they need to bring my tax returns when they are interviewed at the US Consulate. Is this absolutely required, as I'm reluctant to disclose my savings and investments to others including close relatives? Is there a way of getting around it?

I did provide all the required documents (including tax returns) to USCIS during the application process; I just don't feel very comfortable to share such detailed personal information with other grownup siblings (and their families).

Thank you for you attention, and look forward to your advice!