句子成分-through介词短语

各位老师好，下面这个句子，through这个介词词组，是干什么状语？修饰什么部分？

Better to TOP up low wages with public money so that anyone who works has a reasonable income, through a bold expansion of the tax credits that countries such as America and Britain use.

谢谢老师。

介词短语作方法状语，修饰不定式短语“to TOP up low wages...”。

句意：最好是通过大胆扩大美国和英国等国家用的税收抵免，用公共资金来提升低薪资水平，使任何劳动者都有适当的收入。

through构成的介词短语常可用于表示“办法、方法、方法”，又如：

Staff problems should be addressed through training and appraisals.员工问题应该通过培训和考核评定来解决。