I think I can actually help, but I didn't find a way to add links to games. This is my suggestion--
a) Use the "include event sheet" in the eventsheet. Just right click on the eventsheet and look for include eventsheet.
You can then import all the coding you've done from the other eventsheet.
I just found this can cut down on code, because you can make 1 event sheet for character animation and just include it in other eventsheets.
b) Don't-- all you need to do is create a variable (i.e. a score, time, door) that would open the layout.