Mojave tortoise ownership

My family has owned two California desert tortoises since they were hatchlings, the boys are now 10 going on 11. They came from a former coworker of my (late) dad, who ran a tortoise conservatory, but I'm not sure who this person is, if the conservatory is still active, or if the tortoises came with any registration that I can't find. Does anyone have tips on trying to track down this sort of information?

Care tips are also welcome, I'm planning on building them a new enclosure since they keep digging into neighbors' backyards.