If you want the value of the parameter to be updated "manually", just create a parameter of the type "Yes No" with default value "No".
Now create a mapkey to change this value to "YES", Save the mapkey.
I think you have a mapkey for creating a drawing with the same name of active model, just include the new mapkey in the beginning, using nesting technique for example.
This way each time you create a new drawing, the value or the parameter is updated.
Now, if you want Creo to check dynamically if a drawing exists for that model, I think you will need Toolkit or Jlink.
Cheers
Jose