Money, and where the line goes

Decide in advance whether you are lending, giving or investing, and say which one out loud. Most of the damage in family business money comes from nobody naming it: the parent believes it is an investment with a say attached, the child believes it was a gift, and neither finds out until something goes wrong.

If you do put money in, put in an amount whose loss would not change your own plans, and write down what it was for and what happens if it does not work. This is not distrust and it is worth saying so. It is the same thing you would do with anybody else, and doing it properly protects the relationship rather than the money.