The difference between this two sentence

[quicker]

HI...

Do you know what is the difference between :-

"I have to cancel the order" and "I have had to cancel the order"

[Tdol]

I have to cancel = now or future
I have had to cancel = already cancelled

[quicker]

Can I say "I have had to cancel the meeting tomorrow"?

[Tdol]

Yes, if you have already cancelled.

[quicker]

Still a bit confused about "have had" usage.

Can we use "have had" in a forceful way to do something?

For instance, " Amy will be away this Saturday and Sunday as she has had to fly to Australia for compassionate reasons."

From this sentence we can see that Amy hasn't flight to Australia yet. It indicates a future happening but she has no choice and need to go back to her home town for certain reasons.

Does this sentence correctly express the meaning?

[Philly]

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"Amy will be away this Saturday and Sunday..." --> Either "Saturday and Sunday" are in the future or it is now Saturday
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"...as she has had to fly to Australia for compassionate reasons." --> She has already left.
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To have the meaning you describe, the sentence should be:
"Amy will be away this Saturday and Sunday as she has to fly to Australia for compassionate reasons."
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[quicker]

If the mentioned sentence Saturday and Sunday are in future, Can I use "have had" to show future tense with a forceful way.

[risby]

Originally Posted by quicker

If the mentioned sentence Saturday and Sunday are in future, Can I use "have had" to show future tense with a forceful way.

No. Use "will have to" or "must". You cannot have had something in the future. It's got nothing to do with forcefulness.

[Philly]

Hi quicker
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You seem to be confusing the modal verb "have to" with the verb tense called "present perfect".
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Have to:
"Have to" has a meaning similar to "must". "She has to fly" refers to a present and future necessity of a future flight. This sentence uses "have to" in the simple present tense.
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The present perfect tense:
The present perfect (have/has + past participle) is typically used to talk about the past up until now or the recent past.
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"Has had to fly" refers to a finished activity. It uses the present perfect form of "have to". The necessity to fly is finished because the person has already (recently) flown. It refers to the past!
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Question: Why do you want to make the sentence more forceful? Isn't the idea of "have to" (must) strong enough? Or is Amy unwilling to fly?
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