Nest childIds under parentId as IfcRelNests.RelatedObjects (slot 5),
RelatingObject = parent.
A child already nested under one or more DIFFERENT IfcRelNests is
reparented: it is removed from EVERY one of those rels' RelatedObjects
first (a file may legally list a child under more than one nest —
MULTIPLE_NESTING_PARENTS is a diagnostic, not a refusal — so detaching
from only the first one found would leave it still nested under the rest),
tombstoning a rel if that empties it (RelatedObjects is [1:?], so an
emptied list cannot be left as ()), then added to (or its own new) the
target rel.
Nest
childIdsunderparentIdasIfcRelNests.RelatedObjects(slot 5),RelatingObject= parent.A child already nested under one or more DIFFERENT
IfcRelNestsis reparented: it is removed from EVERY one of those rels'RelatedObjectsfirst (a file may legally list a child under more than one nest —MULTIPLE_NESTING_PARENTSis a diagnostic, not a refusal — so detaching from only the first one found would leave it still nested under the rest), tombstoning a rel if that empties it (RelatedObjectsis[1:?], so an emptied list cannot be left as()), then added to (or its own new) the target rel.