I am glad that as the owner you are searching for ideas.

An older dog who can neither see well nor hear well can easily be startled. This "may" account for some of what you described - someone walking past and she goes for the leg. She is relying mostly on scent -- which also diminishes with age -- and she thought it was Jeti when it was your niece.

I know Karen suggested training, but having a dog w/ cognitive impairment now, as well as another who has gone deaf with age, I'm not sure how much can be done as a proactive training sort of thing I think that at this point it is more of anticipating situations and setting things up so things don't happen.

The person staying w/ you for the 4 days should always have a baggie in a pocket with high value treats - cut up hot dog, boiled chicken breast, or bits of cheese. These can be used any time, any place.

If I think of other stuff, I'll come back to this thread.