autodiscoversitescope multivalueproperty

As per Microsoft document on set-clientaccessserver for autodsicoversitescope, it says that @{add=“abc”} will work, however when i have tried that, it is removing everything even existing one. Not sure why.

The successful way was to user -autodiscoversitescope “sitea”,“siteb”

AutoDiscoverSiteScope Property Microsoft.Exchange.Data.MultiValuedProperty`1[[System.String, msco…

following is what Microsoft web site says but seems to be incorrect
o add or remove one or more values without affecting any existing entries, use the following syntax: @{Add="",""…; Remove="",""…}.

Any advise?

 @{add="abc"} 
is a single item ("abc") whereas
 @{add="a","b","c"} 
is a multi-valued object.

Does that work for you?