Hello,
I am looking for anyone that could share a document with me. Does anyone have a form that they have the adult owner (of the minor account) sign that basically make them aware of their responsiblities of the minor account? Hope that made sense?
Thanks!

If the adult is a joint owner, your depositor's contract should already bind them to any liability incurred as a joint owner for actions of other owners. However, you need to review State law prior to granting a minor a checking or savings account.

We actually have a doc that we use for minor checking accounts. The parent (usually) signs the doc that states if the minor account becomes overdrawn, we will transfer funds from the parent designated account to recover the funds. Let me know if you would like to see it.

If we're speaking of a true joint account (multiple-party account), a separate document shouldn't really be needed if your deposit contract reserves the right to offset against other accounts of the account owners. As rlcarey pointed out it's generally covered. Reinventing the wheel could actually cause problems for you if there should be any conflicting verbiage or provisions between the two documents. Just rely on the contract already in place.

If you are talking about some other type of minor account arrangement, obviously that is a different story.