The parents of María Josefa were Antonio Vallejo and Feliciana Alvarez.
María Josefa had a sister named Ana Gertrudis. She married Antonio Anastasio Gutiérrez. They had a daughter named Antonia. The christening godparents of Antonia were Antonio Vallejo and Feliciana Alvarez according to the christening record of Antonia.
María Josefa and Cayetano Romo had a daughter named María de Jesús. Her christening godparents were Antonio Vallejo and Feliciana Alvarez.
Antonia and María de Jesús were born in the same place: Tecameca. It is clear that they were first cousins.
The christening record of Mariana Josefa Bernardina (The daughter of Cayetano Romo and María Josefa Vallejo) closes the circle. Her christening godparents were Ana Gertrudis (The sister of María Josefa) and Anastasio Antonio Gutiérrez.
I marked the parents of María Josefa "uncertain" because there is no source that directly and clearly supports the relationship.
(There are links to the original documents in the text box of each one of the relevant profiles)