the way做先行词时in which和that可以互换,还可以不填.that在这里是指代“the way”,具体成分应具体分析,如I don't like the way (that/in which) he speaks.此时that指代作宾语的the way,严格来说that不做成分,只是定语从句中的一个关系代词.
但当the way 出现在以下句子中,则应另当别论.如：The way she came up with was great,句中the way 作主语,she came up with修饰它,说明其属性,was great 修饰它,此时就不再是定语从句了.
-D