New to Blink myself. The only solution I’ve found is using IFTTT’s “ Arm your Blink when the last person leaves home“ applet, which connects with the Life360 app. Life360 is a social app which you’d need to get all family members to download and enable location tracking for. Life360 then knows when the last family member has left a location (say, Home) and triggers the IFTTT applet.
Really, Blink should have its own solution for this, similar to Nest. Or on iOS use the native Find My app.