According to the City of SD list of communities, Sorrento Valley does not exist. Just Mira Mesa, which is that huge chunk of pink on the map.
I do have to say this is quite odd given most of the communities are much smaller in size, which means Sorrento Valley residents do have a good case to become their own community.
Meanwhile individual communities have no problems joining up together as a singular “community”, for example, Miramar Ranch North and Scripps Miramar Ranch have always operated as essentially one single “community” despite being designated as two separate communities. When Stonebridge came to be, initially they were excluded from the larger Scripps Ranch but now they are fully integrated as part of Scripps Ranch. They fought together to be part of the same council district, and this year Stonebridge is now part of the Scripps Ranch Civil Association.
Same with RB and Carmel Mountain Ranch and Sabre Springs, all three are essentially considered the RB community. Residents of all three communities have no problems stating they live in “RB”. Likewise, folks in Torrey Hills, Del Mar Mesa, and Pacific Highland Ranch have no problems identifying as part of CV.
I say live and let live. If it makes sense, people will group together even though the city designates them as separate entities. Like wise, if a neighborhood has enough of a separate sense of identity, they will eventually go their own way. Mira Mesa’s forced signage may have been the catalyst Sorrento Valley residents needed to motivate them to seek formal separation.