Making someone an officer merely takes a meeting or written consent of the board of directors appointing that person. That said, you don't necessarily need to make someone an officer to do those things. You may be fine with an appropriate power of attorney. This varies by the institution, but before you give some person legal authority to act on behalf of the LLC, i think you should consider alternatives and get advice. It is much cheaper to get advice now than it will to clean up the mess because of mistakes.
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I agree with my colleague, especially to the extent that there may be other ways to accomplish your goal. Unfortunately, this forum is not an ideal venue for having the necessary discussion to give you direct advice on what your next move should be. I’m assuming your LLC has an operating agreement, which would need to be taken into account. If you are a single-member LLC, that may not be an issue, but if there are other members, it is definitely a consideration. In short, there are ways to accomplish your goals, but I would advise sitting down with a business attorney to discuss exactly the circumstances, your goals, and your current business setup. Based on the specifics, an attorney may even be able to guide you to options you haven’t considered—for this situation and perhaps even other parts of the business you didn’t realize needed to be addressed.