Carlos has a sister named Rosa and a brother named Luis. Carlos is married to Mariana, and they have a son named Diego. Rosa is married to Jose, and they have two children, Andrea and Felipe. How might Mariana be related to Andrea and Felipe? Also, what is Diego's relationship to Luis?

Make your response very short.
Mariana, being Carlos's wife, is Andrea and Felipe's aunt by marriage. Andrea and Felipe are the children of Rosa, who is Carlos's biological sister. Therefore, any children Rosa has would be Carlos's niece and nephew, making them also the niece and nephew of Carlos's spouse, Mariana.

Diego is Carlos and Mariana's son, making him Luis's nephew, since Luis is Carlos's brother. Conversely, Luis is Diego's uncle from his father's side of the family.