This is not a question but about a mistake in the text

Question

In English if there are two children then he or she is the elder not the eldest.Eldest is used when there are three or more.

Accepted Answer

Thank you, Alan,
I have found the exercise and the sentence was -
Marielle is our eldest = Marielle est notre aînée
I get your point but would you really say in English -
Marielle is our elder?
That sounds odd to me.
Is not Marielle still the eldest of the two?

Answer

Which text does this refer to Alan ?

Answer

Cécile,It was in this week’s weekend workout. In the writing challenge, “ Father of two”.

Answer

Cécile,I agree. However, I believe the correct sentence should be “Marielle is the elder”. It is common  to hear many grammatical mistakes used in English that have become accepted. No one would turn a hair if they heard “Marielle is our eldest”.Thank you for taking an interest.