What is the ruling on changing the original lineage of one's grandparents when applying for a military job, and what is its effect on the salary?

Changing one's origin and lineage to another father or grandfather falls under the warning mentioned in the Hadith: "Whoever claims lineage to other than his father, while knowing, Paradise is forbidden for him." The matter becomes even worse if the change is for a forbidden trick and deception to obtain what is not rightfully his. The questioner is advised to verbally consult with scholars to clarify the issue.