I like to put multiple textures on top of eachother using alpha masks just like this JME2 totorial:
https://wiki.jmonkeyengine.org/legacy/doku.php/multitexturing?s[]=multiple&s[]=textures
(both hard and software multitexturing)
Is that available/can that be done in JME3 and, if so, how?
Look at the shader sources of the terrain, its probably the simplest example atm.