Hi Jennie
Usually people are started on a lower dose of 5mg then this is upped to 10mg if it's all going well and it's usually advised it's taken at night so I assume that's what you're doing.
I don't think anyone claims " Could the medication be helping improve her memory" it is to slow down the rate of decline so she will continue to get worse but at a slower rate is all although many people do say they see a slight improvement at first.
It's possible that all the family members calling her within an hour is confusing for her and anyway and you can have too many opinions really it should be for those closest to her and seeing her more often to make the call on how she is.
Short term, either continue with the medication and make your concerns known when the 4 week assessment come up as you should see a doctor or consultant when this happens or get a doctor's appointment now and see if they could put her on something else, Aricept springs to mind as although it's active ingredients are the same as Donepezil there are many on here that will tell you that for some people it does seem to work better (on the down side it costs more so Doctors don't always like doing it).
K