Yes.  Adding a Sub doesn't prohibit Atmos capability.

Thanks. Now I have arc+2 era 300+sub gen 3 in my family room and 2 one SL in my bedroom. I will change this with : arc+2 one sl+sub gen 3 in family room, 1 era 300 in bed room and 1 era 300  in the kitchen. Good idea? 

If you want the full benefit of Dolby Atmos and logical use for the Era 300’s 

1. Keep the Era 300’s as surrounds with the Arc and sub
2. Use the Era 100’s in the bedroom and Kitchen

I don’t have era 100 s yet, Sonos are expensive iin Morocco 

Sorry, I meant to say use the One SL’s in the kitchen and bedroom :)