There are 156 different linear combinations in order for Kevin to reference one of his 4 different girl cousins utilizing his own sister to add variation to the reference. In this essay I will...

Utilizing the possible references available to his girl cousin:  1. Cousin 2. Cousin's sister 3. Cousin's sister's sister 4. Cousin's sister's sister's sister 5. Sister's cousin's sister's sister's sister

One can change the linear combination of the girl being placed in each cousin and sister mark within 1-4. For example, one can label the 4 girl cousins A, B, C, D.  For Number 3, the order could be A, B, C A, C, B A, B, D A, C, D A, D, C A, D, B B, A, C.... and so forth