grammar - How to reduce an adverbial clause

I have a sentence:

Ms.Cho relayed her concerns about the company's financial situation while she was having a meeting with the manager.

My friend reduced it:

Ms.Cho relayed her concerns about the company's financial situation having a meeting with the manager.

I think the word while cannot be omitted in this sentence, but he doesn't agree with me.
Is he right?
Please help me! thanks