Change of meaning?

I don't understand the question. You could make any number of changes to the sentence to change the meaning. What are you looking for?

The children are eating dinner.
The adults are eating lunch.
No children are eating lunch.
Are any children eating lunch? (change of word order, no change in the verb)
I don't know why the children are eating lunch.

How can anyone answer that question?

What are you trying to achieve?

The question is: Why is the verb phrase unambiguous? What can you add to the verb phrase to change its meaning? What meaning does the change give it? The children are eating lunch.
Does that help to understand ? I don't have more information :-(

chrismrDoes that help to understand ?

I'm afraid not to me. There are a million ways you could change the sentence. I don't understand what you are trying to achieve. Also, originally you said you didn't want to change the verb phrase. Now it seems that you do.

Perhaps someone else can figure out what you are asking for.

You have changed your question. You first said not to alter the vp.now you say to alter it.