Now, to avoid any hiccups, i sent an email to USCIS and asked them that do they have fingerprints of all of our family members or no ? since i have only one receiving, they respond with confirmation that they have it. So i took a print of that email attached it with application
Although USCIS have everything available online, but you never know who has received your application and if he/she doesnt see fingerprint receiving notice in your application and doesnt take a look online in their system, you can be rejected, so why take that chance ?