您好，移民局发布的STEM延期新政中的确规定了在这类第三方公司工作的OPT学生不具有申请OPT Extension的权利，雇佣关系和填写training plan的雇主必须是同一个雇主，详细内容如下：
There are several aspects of the STEM OPT extension that do not make it apt for
certain types of arrangements, including multiple employer arrangements, sole proprietorships,
employment through “temp” agencies, employment through consulting firm arrangements that
provide labor for hire, and other relationships that do not constitute a bona fide employer-employee
relationship. One concern arises from the difficulty individuals employed through
such arrangements would face in complying with, among other things, the training plan
requirements of this rule. Another concern is the potential for visa fraud arising from such
arrangements. Furthermore, evaluating the merits of such arrangements would be difficult and
create additional burdens for DSOs. Accordingly, DHS clarifies that students cannot qualify for
STEM OPT extensions unless they will be bona fide employees of the employer signing the
Training Plan, and the employer that signs the Training Plan must be the same entity that
employs the student and provides the practical training experience. DHS recognizes that this
outcome is a departure from SEVP’s April 23, 2010 Policy Guidance (1004-03).
24个月延期新政详细内容可以参考：https://www.federalregister.gov/articles/2016/03/11/2016-04828/improving-and-expanding-training-opportunities-for-f-1-nonimmigrant-students-with-stem-degrees-and
