"We have tried CBD oil with small amounts of THC with some success but still cannot find a good balance. "
There's no set dosage or regimen for Alzheimers and I'm not a doctor, but I can share someone's personal experience, which you might find helpful:
When I worked at a cannabis extraction company, my co-worker's grandmother was in a similar situation. He used a high THC concentrate on her and his family found it very helpful. To give you an idea of oil strength, it was somewhere in the ball park of 500mg THC per 1g oil. Oil was a whole plant extract. They said that it just made her happier and helped her sleep. They started with a small rice grain sized amount of oil and just upped it til they got the effect they were seeking. They never gave her a full gram in one dose.
Alzheimer is a degenerative incarnation of Dementia in which there is the building of plaque along with neurons in various parts of the brain.
I don't know the exact cause of it but the result is lack of function in the neurons along which the plaque has grown.
From what I've seen the person suffering from Alzheimer's disease have difficulty in keeping their thoughts together, along with delusions, disorientation, and more.
By the citation of What Is CBD, I somewhat know that hemp based Cannabidiol aka CBD is a pure and potent antioxidant that is known to reduce the oxidative stress that induces the plaque in the first place
So I suggest Hemp derived CBD against Alzheimer.