Thanks for the tip on mirroring of the Muxes to get the DMuxes. And also thank you for all the tips in the various previous replies to other people's posts. I've been reading those and they've been very helpful.
i implemented my DMux4way using a Xor and 3 Dmuxes
how can i know if my implementation is ok
is that the best way?
In general, if your implementation passes the test script, you part is OK. Specifically, the solution talked about in this post is just 3 DMuxes. Don't spend too much time on it, though. Working on DMux8Way may give you insight that will let you go back and improve your 4Way.