Command advertisement can be overwritten by the Command owner, before submission when using OpenDREAMS API. If you wish to overwrite it, you must provide a valid advertisement string like the one presented above to the key ClassAdDesc in JobTemplate's extraProperty map attribute.
Note that there's an "other" macro in both advertisements: in SGA advertisements, other stands for the Command advertisement and vice versa. For futher explanation on how the matchmaking works and features provided by ClassAds, please visit their webpage.
ClassAds webpage: https://research.cs.wisc.edu/htcondor/classad/classad.html