Not sure about your reference to the 2nd Platoon since there was more that one platoon in any company, and several companies in a 4th Armored Battalion.
Yes there is at least one person alive who was at Chaumont on 23 Dec 1944. He is Brig Gen Albin F Irzyk USA retired. In Dec 1944 Al Irzyk, then a Major was made CO of the 8th Tank Battalion, Combat Command B, 4th Armored Division, US 3rd Army under Gen Geo S PAtton jr. His autobiographical account of the 4th Armored, including the rescue of 101st at BAstogne is in his book "He Rode Up Front For Patton" published in 1996 by Pentland Press, Raleigh NC. Major Irzyk led the 4th from Arlon into Bastogne to rescue the entrapped 101st Airborne.
You can read his account of that adventure online at:
Only a few copies of He Rode Up Front are available in libraries across the country. Check www.worldcat.org for possible libraries near you or ask your local library to order one under inter Library loan.
I have talked with Gen Irzyk about his book but do not now have his address or phone number. Best way to contact Gen Irzyk is through Pentland Press, Southeast Florida Chapter VBOB at