"I thought you gave it" is a scheduling problem, not a communication failure.
One person managing medicines is a memory problem. Three people managing medicines is a coordination problem, and it fails differently: not through forgetting, but through each person reasonably assuming somebody else has handled it.
The two failure modes are mirror images. A dose gets given twice because two people both stepped in, or it gets missed because both assumed the other had. Almost every medication reminder product is built for a single user and quietly makes this worse, because each helper sees only their own view.
"Mum's medicines" as a shared responsibility means nobody owns any particular dose. Split by dose instead: the morning one is the attendant's, the evening one is whoever's at home, the night one is the spouse.
Write it down where everyone can see. Verbal arrangements decay within about a fortnight, particularly once someone travels.
Everyone ticking the same sheet is worth more than a group chat. A chat scrolls, gets muted, and nobody scrolls back to check whether the 2pm was given - they just ask, and the asking is the friction that makes people stop.
One chart on the wall near where the medicines live, one row per dose, ticked when given, with initials. Low-tech and it works across people who don't share a phone ecosystem.
Where there's a paid attendant, the handover moment is where most errors live. Two lines is enough: what was given today, and anything that seemed different.
If the attendant changes weekly, keep the record with the medicines rather than with the person. The system has to survive the staff turnover.
The ideal is that the confirmation happens once and everyone sees it, without anyone having to report to anyone else. That's what removes the asking, and the asking is what makes shared care exhausting.
Worth saying plainly, because the wrong tool applied to the wrong problem wastes weeks:
They can if you build it that way. A printed chart in a shared space is the simplest version and works regardless of what phones people use.
A record ticked at the moment of giving. Memory and group chats both fail here, because neither gives a quick answer to 'has this already been done?'
Usually whoever is least involved day to day - often the sibling living furthest away. They have the distance to keep it tidy and it gives them a real job.
Where they're able to be, yes. A system built around someone rather than with them tends to be resisted, and reasonably so.
DailyDawa sends the reminder once, and the confirmation is logged where the family can see it - so nobody has to ask whether the 2pm was given. If it goes unanswered, the nominated person is told.