No problem, I'm not sure if I understand your last question though.
I recommend using an invisible sprite as a spawn point. You do, however, need an instance of the monster sprite in your project, so you can just put a monster sprite on the outside of your layout. (like I did with the "enemy" sprite in the example)
If that didn't answer your question, maybe you could to add an event that does something like this?
System, On start of layout => Destroy monster sprite