For a useless example, here's a solution to Caesar: (narcissus) 3 dip 3 dig (16) (23) between do
A definition of Narcissus that makes this solve work is: 3 zap(3 zap(?)(3 caesar)zap copy format)(3 caesar)zap copy format
You could imagine applying this to something with a long solution like Thirteen to save some symbols on Thirteen, though of course at the cost of making Narcissus longer. You can also construct an even better definition of Narcissus that can detect the input (especially for levels where it is significantly different than those in Narcissus) so you don't need the between.
If you haven't solved Narcissus yet on the savefile, I'm pretty you can just put some code in and it can be used in other levels despite not actually being a quine, so you could just throw a "3 caesar" in Narcissus' textbox with no problem. Once the level is solved once this seems to not work anymore though.
P.S. I removed a bunch of the solutions you added to the side because this isn't a resource for casual solves; it's specifically for symbol optimization. The multiply solution was cool though, so I optimized it a bit and left it in.