Jon - I think this reference idea is a great one. Allow trees to be linked by say, a marriage. Then have options to display/use all linked trees together or view a tree separately. You could have a tree for each of your parents, or each of your grandparents, linked by the marriages. This might also help those people with thousands of individuals in their tree, who find problems with FTM - just work on the smaller trees, and only use the whole tree when you need to for reports etc. FTM could automatically prompt you to start a new linked tree if your main tree gets too big.