Jo, it doesn't sound good.
People can survive pancreatic cancer, but in order to do so it has to be caught early, they have to be young and healthy, they also have to be VERY lucky.
A man I know was diagnosed early, was in his 40s with young children. And even then, they said he had little chance. But they tried. he had chemo and radiation which shrank the tumour, then they finally operated on him once the tumour had shrunk enough, and were even able to save his Islets (so no diabetes following the surgery). He then had more chemo and radiation to kill any remaining tumour cells. It as looking like he was going to make it. The Christmas after he'd been diagnosed, his wife was in total denial and refusing to discuss the possibility that he would not make it - she was insistent that he be surrounded with positive vibes only. But the rest of us did not expect him to reach Easter, and even that was only because he was young, the cancer had been caught early and he had that much time, it seemed.
But the surgery in the New Year went well, the treatment went well. He got fit and strong again, looked after himself (not a drinker or smoker) and enjoyed his time with his baby girls.
He got sick again in October and died a couple of weeks before the next Christmas. The treatment had bought him a year which he valued. But even with everything they threw at him, plus luck, he only had a little more time.
When I was pregnant with easy child, I was in hospital with threatened early labour and a dying placenta. Almost all the other women in that ward had hypertension and/or gestational diabetes. One older woman in my room was a walking stick, she had been so sick and lost so much weight. She had a late-in-life pregnancy, had grandchildren already. But she was happy to be pregnant and her gestational diabetes stabilised fast, so she was allowed home on weekends (unlike most of the other women whose diabetes would fluctuate). This woman lived in the town where my parents-in-law lived, so six months later at Christmas time, we were with our in-laws and our new baby at church, when I saw in the service notes, "flowers to the memory of..." and it was my friend from hospital. I asked the priest as we left the church - the woman had had pancreatic cancer, only diagnosed a week before she died. By that stage she was in a coma. They kept her alive to deliver the baby, then turned off life support.
Pancreatic cancer gallops fast, and is also often too far advanced before it is diagnosed. The bloke with the little girls - he had it picked up early, but it still took him. And he was fit, otherwise healthy and young. Yes, there are new treatments, but I suspect your father in law is sensible to get his affairs in order. Fast.
I'm so sorry. This is going to rebound on you, because this is going to happen too fast for mother in law and H to cope, I suspect.
Might I suggest someone sit with father in law with a tape recorder and get him to talk about his life, his dreams, his ideas? When a person is gone, you can't go back and do this. If he's at all the sort of person who would appreciate being asked to leave a message for the future for his grandchildren, it could be a good way to help other people cope, too.
Marg