分析Until you are old enough,we will make the decision that we

分析Until you are old enough,we will make the decision that we think are best for you.的句子结构
主要是we THINK ARE best for you怎么回事

这句子有问题,你是否输错了?或者原文就有问题?Until 应该为 When,are 应该为 is,正确说法似应为：
When you are old enough,we will make the decision that we think is best for you.
we think 可以看做插入成分,that 和 插入成分we think 后的 is best for you 是定语从句,修饰先行词decision.
全句的意思是：当你真的老了的时候,我们将会做出我们认为最对你好的决定.
现在你应该看的出来,until 是“到.时候”的意思,不是“当.”,所以应改为 when ;而 are该为is 的原因,是考虑到必须与从句的主语decision 保持主谓一致.