Gregoria was the second wife of Santiago Marrero Dávila. She was the mother of Chago (Santiago, 1897) and Borinquen (1898). It is not clear when she became the common-law wife of Santiago, since the death date of his first wife Josefa is not certain. At least one document (Santiago's marriage certificate in 1910) puts it as 1899. Could it have been "mis-remembered" after 10+ years? Given that names and dates in some of the records are often slightly wrong, that is certainly possible. At the same time, the marriage to Josefa was Consensual Contrato (common-law), so divorce was probably not a formal affair.
Gregoria's maternal name is an example of recording errors; it is listed as "Christian" on her marriage certificate, but listed as "Cristian" in almost all other references, including her death certificate.
According to the 1910 Census, Gregoria's mother Maria was from St. Croix, Virgin Islands, and her father Honorio Rios was from Spain. This is the most recent ancestor in this family with a documented lineage from Europe. Rios is a traditional Spanish name. Marrero is not. In looking through early church records from Puerto Rico, online records of those that settled on the island in the earliest years, the name Rios is common. There are no early mentions of Marrero in those records.
Although there are references on the Internet indicating that the name Marrrero originated in Spain, there are very, very few references when attempting to find the name in Spanish records. It is known that an earlier settler to the Canary Islands from Portugal was named Marrero, and my assumption is that almost all Marrero's who did emigrate from Europe came from the Canary Islands, not Spain.
Both isleños and peninsulars ended up in Puerto Rico (Wikipedia article on Canarian migration), and tracing those links can be very difficult. In the case of this family, there is no known documentation of when that occurred, especially on the Marrero side. There was also a mixing with Taino descendents at some point, which is also not documented. Oral history is that the Román line may have originated with a military person, but again, their is no documentation to support that.
The Santiago-Gregoria household in 1910, in addition to Chago and Borinquen, included two people identitied as cousins: Marcolina and Josefa Peterson. There were more likely nieces of Gregoria's sister Maria.