Given that your relative already has a Kindle why not root it and remove their lock-in that way? I know you can put Cyanogen mod on there and would think it likely that Replicant might work too (easy enough to find out by trying it for yourself!). Once a new ROM is in place FB Reader could be added to it. There are many resources out there giving details of how to root these devices...for example http://www.androidpolice.com/2011/12/23/exclusive-how-to-easily-root-the-amazon-kindle-regardless-of-its-software-version/
David Nash
