Thanks Richard for the quick reply. Yes, platform A and B.I just want to know whether my friend approach in modelling displacement on those two platform is correct or not.Like this :

Displacement on platform A:

Dx = -33.43,33.43
Dy = -66.56,66.56
Dz = -33.63,33.63

Displacement on platform B:

Dx = -17.42,17.42
Dy = -37.08,37.08
Dz = -15.57,15.57


On platform A:

vector1 vector2 vector3 vector4
Dx = 50.8500 -50.8500 0.0000 0.0000
Dy = 29.4800 -29.4800 0.0000 0.0000
Dz = 49.2000 -49.2000 0.0000 0.0000
Rx = 0.0000 0.0000 0.0000 0.0000
Ry = 0.0000 0.0000 0.0000 0.0000
Rz = 0.0000 0.0000 0.0000 0.0000

On platform B:

vector1 vector2 vector3 vector4
Dx = 0.0000 0.0000 50.8500 -50.8500
Dy = 0.0000 0.0000 29.4800 -29.4800
Dz = 0.0000 0.0000 49.2000 -49.2000
Rx = 0.0000 0.0000 0.0000 0.0000
Ry = 0.0000 0.0000 0.0000 0.0000
Rz = 0.0000 0.0000 0.0000 0.0000

He is using relative method.For example :

the platform A move -33.43 in negative X direction
The platform B move +17.42 in positive X direction

So the relative direction that platform A is moving is 50.85 to the positive and negative x-direction with respect to the platform B.

Then i will have D1,D2,D3 and D4 n the Static Load Cases.

My question is this approach correct?Or can suggest the correct way to do it.Thanks