Let's analyze the statement step-by-step: Anup recalls:
“He is the son of the father of my daughter’s mother.” Break it down:

1. My daughter’s mother :
   • The mother of Anup's daughter is Anup's wife (assuming traditional family roles).
2. The father of my daughter’s mother :
   • The father of Anup's wife, i.e., Anup's father-in-law.
3. He is the son of the father of my daughter’s mother :
   • "He" (Sandeep) is the son of Anup's father-in-law.

Since Anup's father-in-law is the father of Anup's wife, his son would be Anup's wife's brother. Conclusion:
Sandeep is Anup's brother-in-law.

Final answer:

Sandeep is Anup’s brother-in-law.