Is the salary my uncle receives after retirement permissible, and what is the ruling on him concealing his information, and is his wife permissible for him or forbidden, taking into account that he fled from his first military service and then got a job in another military place with false information?

Changing personal information does not affect the validity of the marriage or the permissibility of the salary. The marriage is valid, and the salary is permissible because it is in exchange for work, not for the name. However, one must repent from forgery unless it was out of necessity to repel injustice. What the family receives after the worker's death may be rightfully due to him or a gift from the employer.