Questions regarding testing

To make it short. My daughter unfortunately had BC dx in her 20's, and passed away years later. My other 2 daughters, now in their early 30's have been doing Mamos/Sono and 6 months later MRI. We were all checked for mutations but they showed all negative. Including my other daughter. Now my daughters are getting anxious about having MRI with contrast often due to side effects that they learned could come from the contrast (once a yr). They did have some benign findings over time.

I am looking for advice, being that they are young, and of course have breast density, could the MRI be dropped? What's the deal with the contrast? It's known that it could affect the brain…We were told that my oldest daughter, who did not have any known mutation and got DX w BC at such an early stage, was a fluke. I need clarity, is that still considered a family History? Different clinicians say different things…In other words, if it didn't show any mutation, is there such a thing as a fluke, for discussion purposes do they really have to be more watchful?

looking forward for advice, momallthetime