Discreet to mean like "tactful" or "euphemistic"?

1. Could the word "discreet" be used to mean like "tactful" or "euphemistic"?

Example: Try to say no in a discreet way (i.e. say no in a careful and euphemistic way so as not to upset/offend someone even if you are rejecting them)
Say: Sorry I'm very busy recently. I'm afraid I couldn't help you.
Don't say: No, I won't help you.

Could I use discreet in this case? Discreet seems to mean more than just tactful/euphemistic to me. I searched on the Internet and couldn't find an example which is used to mean that.

I simply say no in a polite and euphemistic way. I didn't say no in a way which is not easily noticed. I wonder if it has to carry the meaning of tactful but in a way of keeping a low profile or keeping secret. You shouldn't use "discreet" if you are tactful in other ways.

2. It is not discreet of you to ask a female how much she weigh. (i.e. it is rude to ask a female directly how much she weigh)

Could I use discreet in this case?

3. It would be more discreet if you don't come to the party. (i.e. your coming will lead to embarrassing situation. It is a smart and careful move not to show up in order to avoid such embarrassment)

Could I use discreet in this case?

Thank you very much.