When my husband took on Cholov Yisroel, he was advised by his Rov not to inform his parents of this switch and to continue eating Cholov Stam in their home- i.e.- Kashrus is a big enough deal, but “more kosher”?!
We continue to buy only Cholov Yisroel, but when at my in-laws…as long as it’s kosher. Our children accept that we only eat Breyer’s ice cream and Dannon yogurt at Grandma’s…except once, at the grocery, when my 4-year old asked me to pretend I’m Grandma…