There is an ancient Chinese poem about the love between the sun and the moon. 'Hallo...goodbye. Hallo sun as you rise in the sky, goodbye moon as you go down to sleep.'
In the poem the sun and moon are under a contract of love. They are written into a contract which delights them both, a contract of true harmony.
Contracts help us. In a contract that is freely entered, we can set our goals, establish parameters, work towards the enhancement of our deepest desires. In a contract with others, we can draw on the gifts, strengths and insights of other people. We can buld a team, we can work towards common goals as well as helping to enable our team members to achieve theirs.
I believe that people prefer contracts rather than relying on unprepared interactions. Even in a family or especially in a family, it is best not to leave things to the random chance of opinion, judgements or mood. It cannot be assumed that individuals will automatically get on with each other. Better to be like the sun and the moon. Establish a contract.