Are the paternal aunt's daughter and her daughters considered unmarriageable (mahram) if the number of breastfeedings from the paternal aunt was not determined?

"Legitimate suckling is not established except by five certain sucklings. If your aunt is not certain that she suckled you five times, then she is not considered your mother through suckling, and her daughters are not unmarriageable kin to you. However, out of piety and precaution, you should not marry the daughters of this woman, in avoidance of the differing opinions of scholars who hold that suckling is established by a single instance."