搀和 can describe either physical mixing (blending ingredients or having people mingle) or, more often in everyday speech, sticking your nose where it doesn't belong. The meddling sense is negative — 搀和别人的事 ('meddle in someone else's business'). Context and tone make the difference, so when you want to say 'mix' neutrally, you can also use 混合, but 搀和 is more playful or critical.