Before I can ever hope of truly grasping tilakkhana (pativedha), I want to make sure I at least have the basic intellectual understanding of it(pariyatti). This is my understanding, please let me know if I misunderstood anything:
Some of the descriptions given for nicca are:
-sense of safety
-sense of predictability, stability
Anicca would be opposite of those above.
Other descriptions for anicca are:
-without substance like bone without meat
Everything that can be attributed to sabbe sankhara(no substance,bone without meat, no safety, no predictability/stability) can also be attributed to sabbe dhamma as well. Because while sabbe dhamma does not fall under sabbe sankhara, sabbe sankhara does fall under sabbe dhamma. Because sabbe dhamma means everything in this world including nama gotta, which is permanent thus anicca cannot apply to that.