To transform from world location to relative location use [FONT=courier new]InverseTransformPosition:
FVector relativeLoc = GetTransform().InverseTransformPosition(myComponent->GetComponentLocation());
To transform from relative location to world location use [FONT=courier new]TransformPosition:
FVector someRelativeLoc;
FVector worldLoc = GetTransform().TransformPosition(someRelativeLoc);
Hope to have helped