Antivaxx in laws

Just want to see what are your thoughts on in law situation regarding about vaccine/covid vaccine n tests. My in laws n SIL are antivaxx and they don’t believe in covid n they claim covid is another genocide. They refused to get vaccine but want us to take our 3 yrs old to visit them this weekend! They don’t like to go out or be outdoor so if we visit it will be mostly inside the house with them n they live far away 8hrs driving. w We bought l n sent them covid tests n ask them to test before we come. The SIL texted back and said no bc the tests steal dna for china to make bioweapon against Americans and why r we scared if we already vaxxed and how our son will recover quickly if he catch it. We tried to explain to her that it’s not true but she won’t listen and tell us that those tests contain parasite and carcinogens. We we pissed that’s she think its ok for her nephew catch covid?? so we cancelled our plan to come visit for father’s day. We don’t know what to do or how to handle this from now on. We want our son to see his grandparents but we also want to protect him since he’s not vaccinated and this virus is still new. What would you do?