I’m 15 weeks and 1 day pregnant today. I’m also young (18), so this wasn’t planned or expected. When my boyfriend’s parents found out, they asked for a paternity test. On my parents’ advice, I agreed to it. Even though I have nothing to hide, it still felt humiliating.
While pettiness sounds awesome here, I’d argue against it. She may need to deal with these people for 18 years or more, depending on how the situation proceeds. Being petty now could lead to long-term animosity that is unneeded.
I say give them the paternity test, see how they react, then get petty if they continue being shitty.