L is the sister of G. G is the son of M. M is married to D. D is the sister of E. E is the son of C. C is married to S. S is the sister of P. How is L related to E?

G is M's son, and L is G's sister, so L is also M's daughter. M is married to D, and D is E's sister, meaning M is E's sister-in-law (or D's sister relationship). D is the sister of E, and M married D, so L is the daughter of M who is married to D (E's sister). L is E's sister's daughter, i.e., Sister's daughter.