Which colours actually suit fair blonde colouring?

Our family compared wedding hair ideas last Sunday because she wants a modest update before her wedding. She is currently a cool medium blonde, and she does not want guests to notice a sudden or theatrical change. The difficulty is that one sample looks slightly grey under warm lamps, so everyone reaches a different conclusion. One relative prefers a few lighter pieces, while the photographer advised keeping the overall contrast familiar. We decided to stop voting from separate screenshots and compare the same references on one shared screen at normal brightness. Her dress is cool white, and the ceremony includes both a dim room and outdoor portraits. That combination makes consistency across lighting more important than chasing a fashionable label. We used hair color try on as a shared reference. Next we will photograph a few temporary colour pieces in the ceremony room. The stylist can then judge whether soft face-framing pieces is the safest choice. We also plan to keep the dress fabric nearby during the test. How can we keep family opinions from outweighing the stylist's evidence?