Is it permissible to marry one's female cousins if the mother only remembers one suckling, and not the number of other sucklings, with the eldest son?

The daughters of the paternal uncle are not maharim to the questioner, because their mother was unsure about the number of sucklings and only confirmed one suckling. Breastfeeding (that establishes mahramiyyah) is not proven by doubt; the default is that it has not occurred until certainty is achieved. Furthermore, the breastfeeding that prohibits marriage consists of five full and satisfying sucklings. Based on this, it is permissible for the questioner to marry them, though it is more cautious to avoid it due to the existence of a doubt.