The plural possessive form is hamsters'.
A possessive tip-off for a hamster belonging to three sisters could be the phrase "the sisters' hamster." This indicates that the hamster is owned collectively by the three sisters. The use of the plural possessive form shows that the ownership is shared among them.
Singular possessive: secretary's Plural: secretaries Plural possessive: secretaries'
The possessive form of the hamster belonging to my sister is "my sister's hamster".
The plural is relatives. The plural possessive is relatives'.
The plural is lads. The plural possessive is lads'.
Something belonging to more than one hamster would be written as hamsters'. So, "We looked into the hamsters' cage at the pet shop."
The plural form is Mexicans. The plural possessive is Mexicans'.
The plural form is echoes. The plural possessive is echoes'.
The plural form is suffixes. The plural possessive is suffixes'.
The plural form is stepsisters. The plural possessive is stepsisters'.
The plural form is inches. The plural possessive is inches'.
The plural possessive of "Father" is, "Fathers"