I've been thinking about this and remembered a time I was put on the spot by my PILs, although not in quite the same way.
When we were first married DH was working away for three months and in that time I was trying to organise our house move to the other end of the country, so I was travelling up and down organising the new house and trying to find a job while still working part-time at my existing job and staying with my parents. It was a very busy time
We were moving about 250 miles away, which put us about 100 miles away from DH's brother and his family. Our SIL was due to give birth and she actually had the baby two days before I was due to take one of my trips down to the new house.
I'd got a lot organised for a short space of time, job interviews, a meeting with the resettlement officer, some decorating planned and a car full of stuff to take down with me.
I had a phone call from FIL. MIL wanted to come with me because she was missing my DH and wanted to spend some time in his house to think about him.
It really wasn't convenient or ideal to have a guest with me, in a half furnished house, while I had so much to do and so much stuff to take with me. It would have meant leaving a lot behind because when I say the car was full I mean it, boxes of stuff on every seat as well as in the boot.
So I said no. So MIL rang up and cried and said how much she was missing my DH and how she needed to come with me to sit in his house and feel closer to him.
I pointed out he had spent only one night of his life in that house, because we only got it the day before he left the country, and so she would probably feel closer to him in her own house, where he grew up and where she wasn't on her own as I would be out a lot for interviews etc or very busy with the jobs I had to do.
So FIL rang me and told me off and said she was really upset and had to come with me and that she would be fine on her own in the house while I did whatever I had to do and would be happy if I just took her for a drive or let her make a family tea one day.
And then I realised what they were really up to. MIL wanted to come with me so that I could either then take her another 100 miles across the country to visit the new baby or so she could make BIL and SIL bring the baby to us.
PILs had been visiting BIL and SIL the week that she went into labour a couple of weeks early. On the day they left, SIL's mother arrived. I think they were planning to get all the family visits over with before the baby was due so they could hold them off for a bit afterwards and have a bit of peace with the baby. MIL was so jealous that SIL's mum was now there for the birth and she wanted to use me as transport and accommodation and papered over it by claiming to be missing DH and 'needing' to be in his house so she could get within visiting range.
I think 100 miles away is still out of range for a quick visit, but in years to come PILs would often leave BIL and SIL after a visit and arrive unexpectedly at our house because they "were passing" (from their 100 mile detour) and felt like calling in. In the time it took them to just pass our house they could have been nearly at their own. They would usually then invite themselves to stay for the weekend and would make it a week if they thought they could get away with it.
So I said no, she could not come with me. And all hell broke loose, crying, shouting, phone calls, visits, weeping, emotional blackmail and they even turned up just before I was due to set off for one last push to try and convince me to take MIL with me.
I still said no.
And remembering all that, I have decided that your father is NBU to say no OP, and your husband was BU for asking and not taking no for an answer.