As long as their is no contact meaning anything that is transported on clothes shoes etc
Crd generally will only appear again in birds when they are stressed
or things change in the environment since they are carriers
You will always have to make sure you wash between groups or your just back to step one
200 yards seems a ok distance
if the group with the crd are not sneezing or congested it should be fine
Most people that have been incontact with crd generally have a closed flock
Best of luck
btw did you treat the soil when you found that your flock had crd
