My mother is on the very high risk list with instructions not to leave the house. She lives not far from me but we haven’t met up as we are trying to observe the lockdown.
My sister lives round the corner from my parents and is going for walks with my mother at least once a week. Sister’s husband works so they are not an isolated household.
I’ve learned my teenage niece (sis DD) is also going out for regular walks with our mother.
They say they are keeping a safe distance (isn’t that what everyone says???) but I am livid that this is happening.
My mother just says she is bored at home. My sister thinks it is “no issue” as she is at a distance from mother when they’re out.
Why has she been advised to stay at home if a walk is no risk, let alone a walk with someone from a different family home?
I’m annoyed with my Mum but I’m more annoyed with my Dsis for meeting up with her, knowing she’s at risk, and allowing her DD to meet her too.
I think our mother has been out with other family members too so she is probably the instigator but can’t they just say no?! 
I’m not really sure what to do other than saying “Please don’t meet up with our mother for walks”. I’m sure they won’t listen. My father doesn’t really have any influence as my mother gets annoyed when he suggests she stays home.
My mother is at fault for going out but my sis and niece shouldn’t be meeting up outside their households either.
Mental health is important too. I accept that.
Am I overreacting?