The Plural form of a noun is indicated by holding the Y-hand, thumb and 1st finger pointing inward & fingers forward, immediately after the sign for that noun and using the same hand, in the same location, then bringing the balls of thumb and 1st finger together to make Thumb 1st finger hand If the sign for the noun requires the use of both hands, then the plural sign is made with one hand while the other hand is kept stationary. N.B. The sign is only to be used for the Plural form of nouns, NOT for 's or for the 3rd Person Singular of verbs. If it is always thought of as the Plural sign, this confusion cannot arise. For example: books, children.
The Possessive form of a noun in the singular is made by first signing the noun in the singular form; then keeping the hand in the same location, if it is a one-handed sign, changing the hand to CLOSED HAND, back inward-upward & fingers forward-inward, with elbow raised, at same time by elbow action and by wrist action jerking hand one hand breadth outwards. If it is a two-handed sign, the possessive is made with one hand while the other hand is kept stationary. For example: dog's, child's.
The possessive form of a noun in the plural is made by first signing the noun in the plural form, then keeping the hand in the same location, changing the plural hand to CLOSED HAND , back inward-upward & fingers forward-inward, with elbow raised, at the same time by elbow-action and by wrist action jerking hand one hand breadth outwards. If it is a two-handed sign, the plural and possessive signs are made with one hand while the other hand remains stationary. For example: dogs', children's.