"She has dark hair, doesn't she?"

Translation: Mae gwallt tywyll gyda hi, on'd oes?

[tachwedd]

I translated this as 'mae gyda hi wallt tywyll, on'd does?' but it was marked as wrong. Is this not an acceptable alternative or have I mixed up north and south Welsh constructions that aren't actually acceptable?

[ibisc]

Both structures mae gyda/ganddi hi xxx..., mae xxx gyda/ganddi hi... are fine, and both are understood all over Wales.

[tachwedd]

Thanks!