If the household is too small for a whole lamb, they are to share with the nearest neighbor based on the number of people, and apportion the lamb accordingly.
KJV
And if the household be too little for the lamb, let him and his neighbour next unto his house take [it] according to the number of the souls; every man according to his eating shall make your count for the lamb.
ASV
and if the household be too little for a lamb, then shall he and his neighbor next unto his house take one according to the number of the souls; according to every man’s eating ye shall make your count for the lamb.