Although

Although her natural courage and strong character brought her through this stressful time, for some reason Sheila had taken a strong dislike to David Evans. She even brought her mother in on the concerns she was expressing to colleagues about her sense of unease whenever she had any dealings with the man.

Could someone please explain the bold part?

She also discussed these concerns with her mother.

[color=red]She even brought her mother in on the concerns she was expressing to colleagues about her sense of unease whenever she had any dealings with the man.
What is the connection between the two parts above?

She even brought her mother in / on the concerns she was expressing to colleagues / about her sense of unease / whenever she had any dealings with the man.

She discussed her feelings with her mother (as Dozy has explained).
She told her colleagues about her concerns.

Her concerns were about her uneasiness when she had to talk to, contact or work with David Evans.

She even brought her mother in on the concerns[color=red][size=150].[/size] She was expressing to colleagues about her sense of unease whenever she had any dealings with the man.
What about the full stop that I inserted above?

That’s no good because it splits a phrase.

the concerns she was expressing’ must be combined. ‘which she was expressing to colleagues’ indicates that she was telling her colleagues about these concerns.

The sentence was obscure to me those time. But after the answer to the question in my last post makes it clear. Now I work out the sentence. Thanks Beeesneees.