The validity of a prenuptial agreement can sometimes be undermined, even when great care has be exercised in drafting it. For example, two major issues are: a) whether you made full financial disclosure at the time the agreement was signed; b) whether your spouse had an opportunity to be adequately represented by his or her own lawyer. Certain changes in circumstances can also weaken it. This is why even if you do have a prenup, it's not a good idea to assume you are necessarily beyond all legal consequences it is intended to guard against.
Needless to say, it is far better to have a prenuptial agreement than not, but no legal approach is 100% foolproof. The law changes and so do individual situations, and these factors affect the way any court will view and interpret an agreement, especially in a divorce, and in particular where children are concerned. For this reason, it's smart to heed all the other principles outlined in this report even with a prenup, and to approach negotiations from a conciliatory, cost-effective standpoint.
What you agreed to in your prenuptial agreement can also have a bearing on estate planning considerations. When you update your Will, have your lawyer carefully review your prenup. You want to be sure any changes or amendments to the Will are in accord with its provisions. Otherwise, if there is any conflict or ambiguity between the two documents and you die unexpectedly, the Will may be open to challenge and your wishes may not be honored.
Regarding any specific proof or items of evidence pertaining to your prenup, make sure you have all supporting financial documentation collected and in a secure place, like a safe deposit box only you have access to.