Giving Multiple Armatures One Parent I'm starting to dabble in IK rigging and think I bit off more than I can chew. I have a 4 legged tank in which each leg is its own armature. 
I want to be able to rig everything up so that when I move the center base of the tank upwards, the legs will move with it, as if if was lifting itself off the ground. My issue is how to take all four legs and parent their meeting point with one single bone, in which I can then parent the mesh of the body of the tank to.
I understand I more than likely have done all of this wrong, but hey, it's a learning experience. All four legs are rigged up correctly in that the have a range of motion that their meshes would allow. The four bones coming out of the middle are not connected to one another and do not themselves contribute to the movement of the legs. The movement begins where the leg mesh does, which hopefully can be understood better in the picture above.
I apologize if I haven't explained this well, I'm not well versed enough in rigging to know all the lingo and explain it better as of yet.
As Nathan said, it's better to have a single armature, which will be the main animation tool (avoid mixing bones animation with object animation).
Check if all bones of the four legs have unique names (rename them if necessary), then select all four armatures and press Ctrl J to join them into one.
Then create in edit mode a new &quot;center&quot; bone, select the first bone of every leg, shift select the center bone and press Ctrl P (keep offset).
In this way in pose mode moving the center bone will  result in moving all four legs.
Then you can parent the center mesh to the center bone selecting the mesh, shift select the armature, go to pose mode, select the center bone, press Ctrl P (bone option).