I drew a line with my cousin over her 'secret ingredient' in my stocks... now it's awkward.

Every time we cook together, she adds a splash of soy sauce to my simmering stocks... says it adds depth. I've worked hard on my broth base for years, and this changes the whole flavor profile. On one side, I want to respect her input and keep the peace, since cooking is how we connect. On the other, it feels like she's not trusting my methods, and the result isn't what I planned. I gently asked her to hold off last week, and she hasn't offered to help since. Where do you all stand on this? Should you let family tweak your recipes to avoid friction, or stand firm on your craft? I'm really unsure how to handle it...