That, really. DM has (undiagnosed but very obvious) cognitive impairment/dementia. Lives at home with dad, who's OK but starting to get a little more forgetful and elderly. DM is on a couple of different regular medications (for high BP, statins, anxiety/depression), and also has an 'as needed' sleeping pill for insomnia. It's become very obvious that she's taking more meds than she should: my dad tells me this is happening, and the GP keeps refusing to refill her prescription, because she's running out too quickly. I think the reason she's doing it is partly genuine forgetfulness (can't remember if she's taken a pill, so takes another), and partly total confusion about which meds do what (she can't sleep or feels ill, so takes a pill, even though it might be a BP pill which will of course make no difference).
I've repeatedly tried to explain to both DPs that this is a Very Bad Thing and puts her at risk of real harm, but I'm getting nowhere. Dad has tried to stop her doing this, but she refuses to relinquish control of her meds and gets very angry with him if he tries to force the issue. I've bought her a dosette box which she utterly refuses to use. I've emailed her GP to explain my concerns, but I don't have authority to speak to them (trying to get this in place, but not terribly optimistic).
What else can I do?