中译英求助 品质方面的 在线等马上给分

(One of) The customer's customer will have an initial quality-appraisal on the product between October and December,they hope that no change on/variation to the 4M be made during this period.Therefore they send this document for us to sign as an undertaking.

客户的客户在10月~12月期间，对于产品会有一个初期品质评价的时期，
他们希望我们在这段时间里不要对4M进行变更。
所以发出这个文件，希望我们能够签字保证。

The client of our client will have a pre-stage quality evaluation during Oct. ~ Dec.,
and they hope...