Please be aware that the Turbotax license allows the buyer to install up to 5 copies on computers owned by the buyer. It has never been permitted in the license for you to allow your family members to install the program on their computers, even though lots of people did that. The idea of allowing a desktop user to file more than one return is that it will only be installed on computers that you own, and you will use it to prepare the additional returns--not that other people will install the same copy on their computers.
By linking the purchase to an online account, Turbotax is trying to crack down on excessive sharing of the program. When your family members go to install the software on their computers, they will need your Turbotax account user name and password. They could use that access to see your previous online activities.
However, their actual tax returns are individual documents (like a spreadsheet or word processor document) saved to their hard drive, and your tax returns are documents saved to your hard drive and they aren't shared. (Unless you previously used the online version, as mentioned.)
