make one of several Armatures? SOLVED

Hello (again),

Well i have 3 Armatures i’d wish to affect one sole mesh.
I encounter serious problems to get more than one armature to affect the mesh.
I wonder if it woudn’t be better to “stick” these armatures to make a unique one (assigning the groups And/or weightpainting would be much easier). Is it possible?

(I tried with IK Solver… but the weightpainting just doesn’t stick to the bones… don’t understand…)