I'm so sorry to hear your Dad's news but am hopeful that his oncologist will have a treatment plan ready to discuss on Thursday. I've learned that incurable doesn't mean untreatable.

I think the advice to attend alone will be due to COVID and I suggest your Dad ignores it. Through my treatment this past 6 months I have attended alone when it was for things like a scan or pre-op checks, but when I knew I would be receiving a diagnosis or results I took my husband with me - and made him take notes! He's always been welcomed despite what the letter says. I think it's really important that your Mum is there too - to offer support, to be a second pair of ears and to ask her own questions if she would like. I am sure she will be welcome but you could always call up in advance to confirm that she will be coming and, if you do have to have a slightly awkward conversation, then at least it's happened in advance.

Sending very best wishes to all of you.