the grains propagate. That is just more grains. I use them as ricotta, yum! I would be careful pressing them too much because you will damage the structure with harsh treatment but they are not very delicate. As you do it for longer they will all be more gelatinous if you are processing it fast and will be more firm if they are left in a low-sugar/high-acid environment for a few days. That's how you get them ready to travel!
If you are transitioning to a different food source for the microbes, you will have to do it slowly. The stuff that eats lactose is not always the same stuff that eats other sugars. I think the microbes form a semisolid "grain", but the lactose consumers may have special talent for doing it, and you may be better off getting some grains specific for your
feed source. I haven't ever used anything but milk. It can be done though!