Mother-in-law is paranoid about ball pythons...?

My mother-in-law is afraid somebody will find out that we own two ball pythons and call DHS and our son will be taken. These snakes are very tame and I know for a fact that they are harmless, no venom, no fangs, they don't constrict, they will only grow to be 4-5 ft. etc. We take all precautions and are responsible owners, our son is 3 1/2 and doesn't mess with them, we don't even let him hold them even though they are very gentle and have never bitten. They stay in secure containers and never roam free in the house. She knows they cant hurt my son but it's the DHS part she's afraid of. She is paranoid about it to the point that she lies to the foster kids she has telling them that we don't own them, that we are keeping them for somebody and telling them not to tell anybody they're here. I'm tired of her nagging about them all the time and don't really know what to do or say. I don't believe you can get in trouble for owning a harmless pet but cant tell her that. She's one of those that are always in our business and letting us know what we "should" and "shouldn't" do.