creo4 config.pro option documentation for: PART_MP_CALC_IGNORE_ALT_MP 
sim_modal_disp_superposition
Category: Creo Simulate
Description: Specify whether modal displacement superposition should be used in dynamic analyses.
Values: yes, no
Default Values: yes
_6_9_3_123_3" class="Body">By default, to calculate the mass properties, Creo
uses the calculated mass (mass=volume*density). If you set the value of the configuration option to no
then Creo
uses the value of PRO_MP_ALT_MASS
(alternative mass) that you defined to calculate part mass properties if PRO_MP_SOURCE
is Geometry and Parameters
or Fully Assigned
.