Hi, I am currently using a AV600 which is fed via a cat5+ from 1st build(thick walled cottage)to a 2nd build (50ft away) this also feeds a 3rd build (further 20ft away) wireless. 
I now need to improve coverage at 1st build due to dead points. Tried another AV600 which knocked out the others. Have been advised to use a Deco. Will this work with other builds on its own or can I link it together i.e Deco as main then backfeed AV600 ?