You may or may not be found liable, as that depends on the specific facts and circumstances, most of which you will not be able to control. The real concern is that you will be named in any lawsuit, and thus you will be subject to the cost of defense. Call your insurance agent to see if they can issue a Special Events Policy. I have hosted similar events, including a wedding, and that's what I did. Good luck and congratulations on the upcoming wedding.
The above "answer" is for discussion purposes only and is neither intended as legal advice nor to create an attorney-client relationship. An attorney-client relationship is not created until after an in person consultation and I agree in writing to provide representation. I am licensed solely in the state of Arizona. You should consult with a knowledgeable attorney in your jurisdiction.
Generally speaking the answer is likely no; however, the advice about finding out what it would cost to obtain special event insurance is good advice. Even if you are not ultimately responsible getting sued can be expensive in the absence of insurance coverage. You will also want to check the agreement you have the with venue serving the alcohol to see if that agreement is attempting to make you responsible for their actions in serving alcohol to guest. Good luck and congratulations.
This information is provided for general informational purposes and is not intended as legal advice. An attorney licensed in your jurisdiction can answer questions specific to your specific fact situation and provide you appropriate advice as necessary based on the specific facts of your matter and the jurisdiction in which you reside. If you are in Arizona and interested in discussing your matter further I can be reached at: (480) 838-9000 Campbell Law PC 1839 S. Alma School Road, Suite 275 Mesa, Arizona 85210