A notary does not do anything to validate the information contained in a document, so getting something notarized is for the most part valueless. Most brokerage accounts calculate current value based on the market price as of the statement date so something like this should suffice.
Unless you are older than 59 1/2, your IRA funds will likely not be considered because they are not liquid without incurring a penalty upon withdrawal.
As for the "family" money, not sure how you can demonstrate control or continued availability unless it is in your name and you are the owner of the assets.