in nantli, in tatli.

Headword: 
in nantli, in tatli.
Principal English Translation: 

"the mother, the father," a metaphor for the leader of the altepetl, who watches out for the macehualli (commoners) as parents would; typically, but not exclusively, the mother/motherhood is mentioned first; see also separate entries for nantli and tatli (central Mexico, early seventeenth century)
Codex Chimalpahin: Society and Politics in Mexico Tenochtitlan, Tlatelolco, Culhuacan, and Other Nahuatl Altepetl in Central Mexico; The Nahuatl and Spanish Annals and Accounts Collected and Recorded by don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, eds. and transl. Arthur J. O. Anderson and Susan Schroeder (Norman: University of Oklahoma Press, 1997), vol. 2, 192–195.

Orthographic Variants: 
in nantli, in tahtli
Attestations from sources in English: 

Ca tināti ca titati in tetzcuco yn altepetl macihui in ca macehuali tlatoani = We are the mother and father of the altepetl of Texcoco, even if the ruler is only a commoner. (central Mexico, early seventeenth century)
Codex Chimalpahin: Society and Politics in Mexico Tenochtitlan, Tlatelolco, Culhuacan, and Other Nahuatl Altepetl in Central Mexico; The Nahuatl and Spanish Annals and Accounts Collected and Recorded by don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, eds. and transl. Arthur J. O. Anderson and Susan Schroeder (Norman: University of Oklahoma Press, 1997), vol. 2, 200–201.

yn inan yn ita yn macehuali . . . yn tenanti yn tetati yn tetzcoca = Were the commoners' mother and father, [Coanacochtzin,] there? . . . those who have acted as mothers and fathers of the Texcoca (central Mexico, early seventeenth century)
Codex Chimalpahin: Society and Politics in Mexico Tenochtitlan, Tlatelolco, Culhuacan, and Other Nahuatl Altepetl in Central Mexico; The Nahuatl and Spanish Annals and Accounts Collected and Recorded by don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, eds. and transl. Arthur J. O. Anderson and Susan Schroeder (Norman: University of Oklahoma Press, 1997), vol. 2, 192–195.

nenantilo, netatilo = he is made a mother, a father;
inaio, itaio (inayo, itayo) = his motherliness, his fatherliness (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 10 -- The People, No. 14, Part 11, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 59–60.

in naiotll, in taiotl = the motherhood, the fatherhood (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 52.

The Florentine Codex, especially Book 6, also uses the mother/father pairing when speaking of rulers of the altepetl. Note the extensive use of mother/father in the discussion of the head merchant, who was a leader of people. Note also the word order, with mother coming first:
tenan, teta = the mother, the father (of people);
uel tena, uel teta (huel tena, huel teta) = the real mother, the real father;
nanchioalo, tachioalo (nancihualo, tachihualo) = he becomes a mother, a father (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961).

Nextepeoalli, otlamaxalli nicnonantia, nicnotatia. Inin tlatolli intechpa mitoaya in cioa, anozo oquichti = I have made my mother and father the garbage heap, the crossroads. This was said of women or men who congregated on the roads. (central Mexico, sixteenth century)
Thelma D. Sullivan, "Nahuatl Proverbs, Conundrums, and Metaphors, Collected by Sahagún," Estudios de Cultura Náhuatl 4 (1963), 150–151.

In elder speech, "I, your mother, your father," seems to have been said when the father was speaking to the child, in the name of both parents, about proper behavior. See, for example, p. 60, note 25, and pp. 84–86 in the Silva Galeana translation of the Huehuehtlahtolli. (central Mexico, sixteenth century)
Huehuehtlahtolli. Testimonios de la antigua palabra, ed. Librado Silva Galeana y un estudio introductorio por Miguel León-Portilla (México: Secretaría de Educación Pública, Fondo de Cultura Económica, 1991), 60, note 25.

in nānyōtl in tàyōtl = parenthood (central Mexico, 1570–80)
James Lockhart, Nahuatl as Written: Lessons in Older Written Nahuatl, with Copious Examples and Texts (Stanford: Stanford University Press and UCLA Latin American Studies, 2001), 198.

in achto totatzin In achto thonãtzin = our first father and our first mother (early seventeenth century, Central Mexico)
Louise M. Burkhart, Before Guadalupe: The Virgin Mary in Early Colonial Nahuatl Literature, Institute for Mesoamerican Studies Monograph 13 (Albany: University at Albany, 2001), 103.

in jntlatol in oteutlatoque: injc tehoatl omjznantique mjtztatique in atl, in tepetl = they spoke divinely as the made thee mother, made thee father of the city (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 49.

Iece ic popovi, ic ixtlavi in naiotl, in taiotl: auh iece iuhcatzintli, iece ixqujchtzin = However, thereby the motherhood, the fatherhood is satisfied, is complied with (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 54.

inan, yta, in atl, in tepetl in jtepapaccauh, in jteahalticauh: auh in jteixaiopapachocauh = the mother, the father of the city, who are its washers, its bathers of people, and its suppressors of tears (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 75.

auh ca nelli in ie nelli in ie iehoatl vel monantzin, vel motatzin: amo monan in monan, amo mota, in mota = And it is assuredly true that he is thy real mother, thy real father. Thy mother is not thy mother; thy father is not thy father (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 79.