DJ,
Me three - I've been divorced from exW since 2001, we live in separate towns - but we do NOTHING together. We have both attended many functions of my 3 girls; graduations, recitals, ball games, etc. but Never together.
At my older 2's High School graduations, me and W took them (I have always had full custody) - then went with the other d's and stat in the bleachers. After the ceremony exW and her b/f now H got to spend 30 min or so with the grad and other girls..................then me, W and D's all went out for dinner - then home.
Going together would actually give your D false hope of "the family is getting back together" and send her into the tornado of emotions.
Same with Holidays - set times for when the minor kids will be with who, the older kids will have to decide who to be with when. My current arrangements with exW:
odd years D goes to exW's for thanksgiving (Wed night - Sat), is with me on Christmas eve and day - usually with exW for 3 - 4 days of her Christmas break (usually after Christmas day).
even years D goes to exW's for 24th - 26th of Dec (plus or minus a day or two depending on school days off and my travel plans) and spends thanksgiving with me and W.
You could split the day - but splitting time off of school usually works better.