If "واو العطف" is used, then all of the words are ma3toof on the first word. Amr and Bakr are ma3toof on Zayd.
If you are using "ثم" or "ف", then the word is ma3toof on the preceding words. E.g.
جاء زيد وعمرو ثم بكر
Amr is ma3toof on Zayd. Bakr is ma3toof on Amr.