It depends. You may be stepsisters- your parents split up and your Dad gets a new wife and has a daughter, your sister. What if they brake up and your sister's step mother has another child? Then no,...
because brothers and brothers.
No, they`d be the second sisters great nieces and nephews
Marques Houston
Ummm... I think so because the sister's cousin has to be related to you unless she is a stepsister.