Is it possible to update multiple Adafruit feeds at once with the HTTP/REST API?

Question

I've inherited an existing project that updates several Adafruit feeds using one curl call per feed. In other words for a set of feeds https://io.adafruit.com/$username/feeds/$dashboardname.$feedname it makes one call to curl for each $feedname that it needs to send data to, which is slow and resource-intensive. Is there a mechanism for updating each of the $feedname's using a single curl call? A bunch of Googling indicates that it might be possible using JSON, but the format required doesn't seem to be documented anywhere. Trial and error with various guesses at JSON hasn't produced useful results.