Family foundations... how do you assign credit?

I need some advice on how to handle gifts from family foundations. We have a good number of families that have a long history of giving to our organization through their family foundations, and we struggle with knowing if/when to soft-credit these gifts to the family members. Some of the gifts are easy... annual fund and membership renewals get soft-credited to the individual renewing his/her own membership. This means that when prospect lists get pulled for the next year, only that individual will pull for annual fund renewal. Easy, great. Some of the gifts are NOT easy... capital campaign gifts, for example. By default, should we soft-credit ALL of the family members who have a relationship with us? And if/when the gift is soft-credited, does each family member get assigned the full amount? Or should we assign the full amount to one family member, and assign $0 to the others, so that they are at least connected to the gift? Where this issue comes up, for example, is when our CEO requests a list of our top donors, and wants to see how much each has given in the last five years. If the gift is not soft-credited, the report is skewed...makes it look like the donor hasn't done much of anything for us. So, ok, we absolutely must soft credit for that reason. However, if the gift is soft-credited, firstly who gets the credit, and secondly if it's soft-credited to more than one person, then all of them will appear on our prospect lists (because we soft-credit donor-advised gifts to the individuals, we credit soft-credited gifts to the soft credit recipients in our prospect lists). I'm always looking for documented policies, if anyone has them to share, otherwise some advice here would be greatly appreciated.