The possessive form of the plural noun Andersens is Andersens'.
Example: The Andersens' house is on the corner.
The plural is relatives. The plural possessive is relatives'.
The plural is lads. The plural possessive is lads'.
The plural form is Mexicans. The plural possessive is Mexicans'.
The plural form is suffixes. The plural possessive is suffixes'.
The plural possessive of stepsister is stepsisters'.
The plural form is inches. The plural possessive is inches'.
The plural form is echoes. The plural possessive is echoes'.
Coaster's is singular possessive. The plural is coasters, the plural possessive is coasters'.
The plural possessive is pals'.
The plural possessive of bandit is bandits'.
Studies' is the plural possessive of study.
The plural possessive form of "weeks" is "weeks'."