23 yo & 7yo don't get on!

[oddleofnoodle]

My first born is 23 and my last is 7 years old. My 7yo is intense, loud and defiant. Nothing can be said quietly and she has an awful habit of repeating things over and over or getting right up into your face to tell you something.
My 23 year old has been with my 7yo (although my 23 lives with her father) for maybe 6 months now as I have came home from Australia). She tries hard to bond but, a lot of the behaviours my 7 year old display can be trying. My 23 year old tells her off quite frequently for this behaviour which annoys me a lot as I feel I should be the one telling her off not my eldest daughter.
How do I help the two of them bond? I don't want my eldest to reduce her visits due to my youngest childs behaviour?

I feel I should also add my 23 year old and 7 year old have different fathers. I moved to Australia in 2017 and my eldest stayed in Northern Ireland with her Father.

Pull up your 7 year old on her annoying behaviour.
My 3yr old does the repetitive phrases/questions all loudly and in your face. I tell him to stop, 3 chances to stop, third time he goes and sits in the kitchen/his room. If you pull 7yr old up on this your 23yr old won't have to, and they can then spend the time enjoying each other's company