This is DH's repeatedly suggestion, inspired by Ellen Wilkinson. Like the namesake, but is Ellen a bit 'meh'?
Apart from thinking it's a bit dull, my concerns would be-
She would get called Ellie which I'm not keen on & is mega popular (like Elle, Nell & Lennie as nns though)
People would think her name is Helen (nice name but DD1 already has a name which is often misheard & it has led to confusion)
DD1's name is a diminuitive of Elizabeth which is on her BC- is Ellen too similar?
Is it a bit weak & feeble? Part of me thinks it's elegant & fab, but