The plural of buoy is buoys.
The plural possessive is buoys'.
Example: The buoys' positions are marked on this map.
The plural for for buoy is buoys; the plural form for valley is valleys.
The singular possessive form is heart's; the plural possessive form is hearts'.
The plural form is founders. The plural possessive is founders'.
Buoys
The plural form for the noun sergeant is sergeants; the plural possessive form is sergeants'.
The singular possessive form for the noun knife is knife's.The plural form is knives; the plural possessive form is knives'.
The noun 'sister' is not plural and is not possessive.The plural form is sisters.The possessive form is sister's.The plural possessive form is sisters'.
The singular form is goose; the singular possessive form is goose's.The plural form is geese; the plural possessive form is geese's.
The plural possessive form of "cherubim" is "cherubim's."
The plural form is valleys. The plural possessive is valleys'.
The plural form is squirrels. The plural possessive is squirrels'.
The plural form is cockroaches; the plural possessive form is cockroaches'.