Working for family

Jackmydad

If the person doing the work was in business doing that work professionally, then I'd expect to pay, but hope to get "mates rates" for the job.
Retired, and offered to do the work without mention of payment. I'd be surprised to be billed for labour, although I'd expect to pay for materials. I'd offer something reasonable for the work done though.
This reminds me slightly of something I mentioned elsewhere on these forums, where a "good friend" was happy to accept me spending several hours of my own work time in tutoring them to do something technical, but when they did a small job for me wanted payment.

Personally, I'd pay FIL by cheque. I'd post it with a copy of the receipt.
He wants to keep it on a business footing. That's what he'd get.

I wouldn't fall out with him about it. If he wanted to fall out with me I'd see it as his loss.
I'd accept no further help from him, and I wouldn't help him in future either.
I'm hard nosed about stuff like that though.

*Robin*

Personally, faced with this situation I'd wonder:
A. Is there a [shameful? ..gambling maybe?] urgent money problem.
B. Medical issue [failing mental faculties?].