I don't know about KPKSC but in FPSC once you claim a domocile its going to remain the same and even if you change your domicile later and appear in CSS they will with-hold your result and your domicile will not be accepted.

Here is an excerpt from FPSC Guidelines for General Recruitment...Rules#7 section V

V.) The domicile claimed by a candidate and accepted by the Government at the time of first entry into Government
service shall be treated as final throughout his/her service career and no subsequent change in his/her domicile will
be recognized for the purpose of terms & conditions of his/her service including his/her allocation and liability to
transfer.

GENERAL INSTRUCTIONS FPSC

JazakAllah

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