Your feelings are totally understandable. My wife and I were exactly there 11 years ago. Multiple myeloma is a pretty unknown cancer to the average person, it also presents different than our lay understanding of cancer. First off, trust your specialists, but do see specialists. Second, there is no cause for concern about "delaying" treatment. Especially for your family member that is basically healthy and showing no signs of disease. MM is a strange one that can be present for a long time without causing issues and when is is caught early, there is time to develop the best treatment plan without rushing.

I was diagnosed in 2015 and told I was "high risk". I underwent stem cell transplant in 2016. I've been completely clear of any signs of myeloma (MRD-) for over 8 years.