Boudicca
Seaside Queen
Yes, I think you are probably right. We are a household if not a family.It's all she could reasonably be expected to do. She's got a right to prepare food in her own home. Risk should be minimal tbh.
Ventilation is a good idea.
Open windows for a while.
Yes, I've asked her to close the kitchen door and open a window if she is in there. The door is not usually closed so it is a signal to the others to stay away. Also offered to cook and shop if she gets too unwell.
I did spend some time chatting with her in the kitchen on Thursday so I guess I should get a PCR.