Who was The Mother of INDRA AND Ashura? Who was Hogoromo’s Wife? Could He had married an Uzumaki Woman? or Could Hogoromo had a Daughter who founded the Uzumaki Clan the same as Ashura founded the Senju and Indra founded the Uchiha Clan remember Males in old time were always mention but females tended to be disregarded unless they did something spectacular like Kaguya did.
At the beginning , we were taught that Kaguya had only one child , only to understand later that this was a lie from BZ.
Kaguya had 2 twins.
The theory of the 3rd child is possible , as there is nothing to counter it , we can't trust what the characters say in the manga , some do but we can't.
If Hagoromo had a third child , that implies that he is lying to Naruto by omission.
Why does he want to hide this part of the story to Naruto?
The uchiha clan would be as distant blood relatives to Senju as Uzumaki are , and the distance is short , they were brothers and sisters , Kushina's "distant blood relatives" would be strange...
Hagoromo's wife and Kaguya's husband are theorical , as they were never mentionned plus Kaguya and Hagoromo both have the ability to use COAT , they may not need fecondation to create a baby.
But there is also no proof that they don't exist.
If Hagoromo's wife was a Uzumaki , why would Kushina say that Senju are distant blood relatives to Uzumaki?
As Ashura's mother , that Uzumaki girl would be the ancestor of the Senju clan , the blood relation would be direct not distant.
That's why I came with the idea that the Uzumaki clan could be founded from the sister of the guy that married Kaguya , or from the brother of the women that married Hagoromo.
In that way , every descendant of the brother of the women who married with Hagoromo would share genes with every descendant of Hagoromo without being their direct descendants or direct ancestors.
The Uzumaki clan would be distant blood related to the Senju clan , the son of the founder of the Uzumaki clan would be Ashura's and Indra's cousin..