TEXAS RULES OF CIVIL PROCEDURE / RULE 64
TRCP 64: Amended instrument
Identifying an amended pleading and filing an entire, complete substitute.
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Read the official rule ↗Rule 64, illustrated

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The party amending shall point out the instrument amended, as "original petition," or "plaintiff's first supplemental petition," or as "original answer," or "defendant's first supplemental answer" or other instrument file by the party and shall amend by filing a substitute therefor, entire and complete in itself, indorsed "amended original petition," or "amended first supplemental petition," or "amended original answer," or "amended first supplemental answer," accordingly as said instruments of pleading are designated.