OP was asking how to interact with their father when he stutters. If you're saying that OP should tell their father to do these things, I have to disagree. Fluent people telling people who stutter what to do when they stutter is incredibly condescending and (in my experience) distracting. Yes, you can stutter with your teeth together?? There are plenty of consonant sounds that require your teeth together, and there isn't one single sound that I've never stuttered on. Once again, the question in this post was about how to react when someone else is stuttering. Not how to "relearn to talk" or how to get out of a stuttering situation. OP does not stutter, so this advice is not necessary.