Texas Local Government Code - LOC GOV'T § 192.003. Records of New or Enlarged County

(a) If a new county is created in whole or in part from the territory of another county or if territory is added to an existing county from another county, the commissioners court of the new county or the enlarged county shall require the county clerk to rerecord each deed, mortgage, conveyance, encumbrance, or muniment of title that affects or relates to real property in the territory taken from the other county and that is recorded in the other county. If the territory is acquired from more than one county, the clerk shall maintain separate sets of records for the records obtained from each county. The records shall be indexed and arranged as provided by law.

(b) After the records are legibly rerecorded, the county clerk or the clerk's deputies who rerecorded them shall compare them with the original record. The county clerk or the clerk's deputies who rerecorded the records shall certify to the correctness of the records under their official oath and shall impress the commissioners court's seal on the records.