Gyda ei gilydd

Thank you for your response…

together: gyda ei gilydd.

Aeth y bechgyn gyda ei gilydd.

If the persons are all female, should it not become gyda ei chilydd?

Aeth y ferched gyda ei chilydd?

But I can’t find any example of this.

Diolch am unrhyw ateb

Ian, Machynlleth

No, because the word cilydd no longer exists outside of the phrase “ei gilydd”, so the phrase is taken as a whole. (cilydd originally meant ‘a fellow’, so was only a male noun anyway)