Body is related to Limb. Limb is the opposite of Whole. 
Sibling is the opposite of Cousin. Cousin is related to Child. you are likely to find Child in/at/on Pen. 
Body <--RelatedTo--> Limb <--Antonym--> Whole 
Sibling <--Antonym--> Cousin <--RelatedTo--> Child --AtLocation--> Pen 