Can we use causative have with modal must. Suppose
- you must have had those document published by you.
- you must have the documents prepared by someone.
Are these idiomatic and grammatical. actually i am experimenting with these.
Yes you can, although this grammar has a fairly specific usage. Ordinarily it expresses a perceived reason for something, for example:
These documents must have been written by you, (because ...)
These documents must have been prepared by someone else (because ...)
This can also be used to describe a situation:
"She must have come here before us -- look, you can see the tracks of her shoes in the snow!" Edward shouted. "Quick, don't let her get away!"
or a person: