Homeowners's is not actually a word.
The singular noun is homeowner and the plural noun is homeowners.
Therefore, the singular possessive noun is homeowner's and the plural possessive noun is homeowners'. There is no extra s on the end.
The plural of homeowner is homeowners.
Singular possessive: secretary's Plural: secretaries Plural possessive: secretaries'
The plural is relatives. The plural possessive is relatives'.
The plural is lads. The plural possessive is lads'.
The plural form is echoes. The plural possessive is echoes'.
The plural form is suffixes. The plural possessive is suffixes'.
The plural form is Mexicans. The plural possessive is Mexicans'.
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"
The plural possessive of bandit is bandits'.
Studies' is the plural possessive of study.