what's in here?

[shang26]

I'll try to explain this as easy as possible, lets say we have a square and a sphere, these objects are connected to other objects and cant be parented as it would create a dependancy loop (float limit out of the question then),

the position of the sphere should be limited to the position of the square, so lets say the sphere can move a distance of 50 in x,y,z from the squares position. How can I do this not using a float limit?