Charities thinking of working together should draw up 'prenuptial agreements', according to the NCVO.
The umbrella body has published guidelines on how partners in the voluntary sector should go about tying the knot.
"We recommend being open with your potential partner, and setting out a written agreement before committing," said Kate Aldous, manager of the Collaborative Working Unit at the NCVO.
"The process of putting it together can help to identify potential problems and misunderstandings. The finished product can give clarity and focus to your work and help you to review your partnership."
The guidance, which is available on the NCVO website, outlines the reasons for creating an agreement and includes advice on resolving disputes between partners.