我需要给每个孩子设一个529账户码？

请教各位大侠：

我是应该给每个孩子设一个529账户呐？还是给他们设一个账户 (since "The beneficiary can be changed to an eligible member of the original beneficiary's family at any time without penalty") ？

(1) 我可不可以将主要的基金放到小一点的孩子名下让老大用。(2) 这样做是不是有利于老大申请scholarship/assistantship/fellowship?

谢谢指教