Reminder that the legendary dragons are NOT actually related (except I THINK Longan and Dragoneye) when Longan refers to them as "kin" they likely mean it as in of the same species.
This is seen in other media with creatures of the same species, such as in Baldur's Gate 3, the tieflings refer to each other as "kin" even if they aren't biological family.
It's more likely that they view each other as family in the sense of found family, Which has been a trope since forever.
Anyways, Pitaya Dragon and Ananas Dragon Cookie should kiss