What is the ruling on marrying a cousin (daughter of a maternal aunt) if her sister was breastfed by the mother without milk at the age of five?

You are permitted to marry this girl because she was not suckled by your mother. The fact that her sister was suckled by your mother does not make her unlawful for you. So, how much more so when her sister was not suckled by your mother at all, due to the absence of milk in your mother's breast at the time of her suckling?