How to request--You cannot request a team, you can only request one individual. The reason is that the teams may shift from one week to the next and almost always change at least every 60 days to allow for vacations, etc. Each time we have made more than one request (A for server OR B for assistant), DCL has messed it up; when you only make one request, they usually manage it. The other issue is that a great assistant is commonly promoted to server within a contract or two.
Anyhow, you (TA must do this if you used one) call DCL and tell them that you want Joe from wherever as your server. THey will tell you that this is only a request and cannot be guaranteed, etc. Just ask them politely to put the notation on the reservation. Then, after boarding, go to "Dining Changes" and ask if you got what you wanted...if not, ask if you can be moved.
Note--you cannot request both a rotation and a particular dining team member...again, if that server/head server/whatever isn't on that rotation, they won't know what matters most to you.
I would highly recommend Angelina from Chile--she had a vacation in January. The assistant was OK, but Angelina was totally amazing. Hour super head server has moved to the Fantasy, so no recommendation there. Andrea from Croatia is on the Magic in Palo and is great. There is also a woman from Turkey and I always get this name wrong--Nergit or Negrit...ditto in Palo.
When you make a request, be sure you have the terminology correct. In your post, you say the head server was OK. Do you mean the head server (supervisor over about 8 serving teams) or do you mean the server? I'm making the point because if you say Joe from somewhere as head server and there is no such person in that position, you don't know what they will do. Your "team" will be a head server (supervisor), server (brings your food), and assistant server (in charge of beverages). While you may not see the head server much, they all work together to give you a great experience.
