@motherhen27
I agree in an ideal world two people co parent amicably and maturely. I agree dramatics are best avoided and we don’t want any children to feel, or be, neglected, ill etc.
For whatever reason - and we won’t know why because neither mum, or dad, or SD is here to tell us the backstory - in this situation the parents don’t agree about delaying the visit. There may be any amount of “whatfuckery” previous to this moment. Regardless, as the parents strongly disagree about what to do here, there is a chance SD isn’t living in this magical perfect family land where she knows she is loved equally by both parents at both homes.
Dad needs to have a chat with his 15 year old daughter directly. So SD understands she is loved (and has heard it from him!), so she understands the risks to her little sister, and so her father can hear her opinion, even if he chooses to insist she stay with mum to prevent infection.
I don’t agree with obscenities of “your a shxt dad” - perhaps if mum was here she’d be able to clear up what she meant by that for us - but I can understand mum suggesting dad handles it with SD.
I also understand SM wants to protect her baby from infection.
All of this is part of the landscape you learn to navigate when you welcome a SC as part of your family! A lack of critical thinking might lead you to believe it was as simple as ringing mum to say you can’t have SD!