The message can occur if you run NX under Teamcenter, possibly also other PLM systems.
You do have the ability to modify the assembly structure , including the position of the components in Teamcenter.
In the other thread you give examples of where a component had been replaced/ substituted in the stucture - in Teamcenter.
"The following substituted component in Teamcenter has been found:
VNMVS-0228/01.001 replaced with VNMVS-0047/01.001"
This is all correct and as it should work.
You can also move components in Teamcenter, ( Personally i think this option is s bit weird ) I do not think we can do an exact move ( say 4 mm +XC) why the opinion "weird".
This is done in the Structure Editor - Viewer. If you then leave the Structure editor by File Save, you will get the message in NX "Child position Not Updated (Mating Conditions Present)" ( in case you have assembly constraints.) If no constraints the component will move in NX.
Anyhow, i have seen quite a few examples of these messages appearing when there has not been a change done in Teamcenter.
I assume that there is some miniature difference in component position which gives the message.
I think you can ignore it.
You can compare the position data between NX and Teamcenter to see if the difference is worth bothering.
When you save the NX assembly, NX will overwrite the component position information in Teamcenter.
Regards,
Tomas