I co-own and run a small business, with a family member. Previously I worked in a similar professional role, but an unrelated industry, for 10 yrs prior to coming into the family business, which was meant to be a temporary role to help out.
We have proper contracts & use an independent accountant to run a proper payroll, therefore pension & dividends etc. I probably earn slightly below market, but have a lot of flexibility and the advantages of share options.
We try to be very respectful in work, and make sure non-family employees are not kept out of the loop. We don't use kinship names in emails for example.
We do slip into talking about work during family times. we do have probably more robust conversations than normal colleagues, especially if I feel my ideas are dismissed or opinion not heard. We have different, very specific areas of specialism which I think helps, we try to stay in our own lane. On the whole we are very respectful, especially as a professional services company.
I am very conscious not to been seen to be taking the piss, for example- all my expenses are double checked & I put in a holiday form. I have heard horror stories where families have been torn apart due to businesses going wrong, or one family member feeling more entitled.