I feel your pain jumping out of the words you wrote. These people are well meaning, or so they say. Fluency is easy to say -- for the fluent. This is probably not your first interaction. Nor will it be your last. When I was a kid, everything about stuttering was anxiety, breathing, annunciation, relaxation, therapy, etc. Largely, it was topical remedies being presented as a cure, like a band-aid. Fast-forward 50 years and it has truly become a neurological science when defining stuttering. For many it can become a controllable, not curable, condition. For others, stuttering knows no bounds. In either instance, the person has a shared relationship with stuttering...and stuttering will always hold the upper hand. I know for me, I can go months having fairly good fluency in the 90% range. And then something just clicks and I can't utter a sentence for weeks or months. For others, they can massage their stuttering into being largely fluent and cover it with tricks and anecdotal remedies that work for them. And still others that go through life with a variety of blocks. No amount of advice is going to ease your frustration. I would say ignore it, but that won't soothe the pain of that chronic family member riding you. To say cheer up, would do nothing but piss me off (and maybe you too). So I offer you none of those. Instead, I commiserate with your situation and know it well.