Look on the tag on the soft good, call that company and ask them. As far as what you need to "fireproof", most places just require backpainting everything, and in some instances require actual fireproof solution to be applied to all surfaces, usually though you have to be using pyro to get to that level.
BUT. YOU MUST CONTACT YOUR LOCAL FIREMARSHAL, RULES ARE DIFFERENT ACCROSS THE ENTIRE COUNTRY, DO NOT TAKE ANY ADVICE HERE FOR LAW, YOU MUST CONTACT YOUR LOCAL FIREMARSHAL.
Some places require a fire marshal inspection before every show opens, some don't. Just depends on the area and what type of suppression is available at the
theatre.