It's not possible to sync backwards from Kindle to Blinkist. Once you send a Blink to Kindle, any reading and/or highlights that you make while on your Kindle will not sync back to the Blinkist app. Send-to-Kindle is simply that: a one-way sending from Blinkist to Kindle, with no reciprocal syncing.
Syncing from Kindle to Blinkist - Is it possible?
