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calm down

further is comparative
far - farther - farthest (physical distance)
far - further - furthest (nonphysical/metaphorical)

You would say "Is it far to the airport?"
BUT "Is it much farther to the...

It's perfectly okay, except the stress of the sentence changes.

In the 1st case you are stressing that Jill will be in Ottawa
In the 2nd case you are stressing that something will happen/be the...

"They are after leaving" = так на английском сказать нельзя. Что вы хотите этим предложением сказать? (this is not a correct English sentence. What are you trying to say?)