Krista Conley Lincoln, the chief executive of Cambridge Translation Resources, a Boston-based translation and publishing company with sales of $2 million, recommends putting everything related to family loans in writing. When Lincoln started her company, in 1992, she borrowed $6,000 from her father. However, she knew that family loans can cause permanent damage to important relationships. So she and her father drew up a formal letter that spelled out both of their terms in detail. "I agreed to pay him back within 18 months, and he promised to never mention the loan, especially not at family dinners or Christmas holidays," Lincoln recalls. "And we both lived up to our promises!"