My 83 yo grandmother moved in with my parents (60yo&61yo) in March to isolate with them during coronavirus. My grandmother has a history of persistent chest infections requiring steroid inhalers (she's currently on one). My mother went through surgery, chemo and radiotherapy for breast cancer last year and is on hormone treatment, and so her immunity is lower than the average person. None of them have left the boundaries of their house since 18th March - anything they have needed has been delivered to their door.
My 3 aunts who live in separate households, and are my granny's daughters and mums sisters, have started visiting. It began with them speaking to my granny on the phone while looking through the window. However they said the sound quality on the phone wasn't good enough and have asked that my granny come into the garden to speak to them, which has happened twice now. They have stayed 6+ft apart and no physical contact.
I called them and asked that from now on if they must visit that they speak to her through the window to avoid any risk of her getting the virus, and avoid risk to my parents. They have refused, saying that they believe its in the best interests of my granny's mental health to see her in the garden where they can talk freely. They believe they are posing no risk in the actions they are taking.
Is my request unreasonable?