Counter letters are no longer recognized in LA law. A simulation is just a term that recognizes that certain transactions can be deemed not authentic (if that makes sense). They are not “legal” by definition.
Just to add to this interesting topic, it used to be common for politicians to know, for example, where a certain bridge was going to be build across the Mississippi. The politician would then buy up all the land where the bridge was going but use someone else’s name on the sale (for obvious reasons). A counter-letter would also be prepared saying who the real owner (the politician) was. The counter-letter would not be recorded. As Oliver Hardy would say: “And no one will be the wiser”.