In a second or third marriage, a child from an earlier marriage may be close to a different adult than a child from the current marriage. In these situations and others, you will want to choose the personal guardian you believe would be best able to care for each child. Some parents name one person to be the children's personal guardian and a different person to look after financial matters. Often this is because the person who would be the best surrogate parent would not be the best person to handle the money. Perhaps you have a close friend who cares about your kids and would be better at dealing with the economic aspects of bringing them up.
Most people have strong feelings about how they want their children to be raised.
Your concerns may cover anything from religious teachings to what college you'd like your child to attend. One option is to write a letter to the personal guardian, outlining thoughts and feelings about how the children should be raised. The best guarantee of an upbringing you would approve of, however, is simply to choose someone who knows you and your children well, and whom you trust to navigate life's complexities on your children's behalf. If one of a child's parents dies, the other parent usually takes responsibility for raising the child. This, of course, is what most people want.