I think in this situation there is no point using grid
because if you have functional lego style components that can essentially stick to each other of predefined surfaces all you need to do is just stick them together.

so there is no reason why you cannot replace the neck with another leg while head will be stuck in place of the foot. since leg component has its own functionality it will be able to move head just as it was foot.

in that situation, I guess it would be more rational to unify all functional components, and just give set joints sticks, tentacles. while you can put some decorations/tools on their ends.

as you, for example, coud put some horn on the arm and computer will recognize is as possible tools/weapon so when fighting another beast it will use that horn to do damage or for the defense. and just move everything in the way to stab than horn into the opponent
If the character has several heads probably every head would be responsible for control of certain joints so if it gets amputated character loses control over those joints.