My uncle passed. He never married. When he became ill in 2006 we added his partner on sertain accounts for emergency purposes.

You question raises more questions: the primary one being - what did your uncle want? Did he leave a Will? If he did not leave a Will, the answers are all in the Illinois Probate Act, which is the default "estate plan" for anyone who has not done a Will. Without a Will, property will be distributed according to the rules of descent and distribution found at Section 2-1 of the Probate Act (755 ILCS 5/2-1). I am assuming that there is no surviving spouse in the picture, and your involvement as a niece or nephew suggests that there are no surviving children. When there is no spouse or descendants, the next line of distribution is parents and sibling (with a double portion to a parent if the other parent has predeceased and the share of a deceased sibling drops down to the siblings descendants). As for the account, your notarized letter will have no effect on the outcome. The key is how the account was set up when the "partner" was added. If she was added "for convenience only," then she has no ownership interest in the account, and she has no claim to the funds today. If she was added as a "joint tenant," then the account is now hers as the surviving joint tenant, and you have no claim in it. This answer is not intended to create an attorney/client relationship. Please understand that the answer provides general statements of the law. Specific facts and circumstances may require a different determination. You should seek the help of local counsel familiar with estates and probate and determine how the estate should be handled and who are the lawful heirs and beneficiaries of the things your uncle left behind.