The specification is not clear as whether a given Child Node can have one or multiple parent.

7.5 HasChild ReferenceType ToC Previous Next
The HasChild ReferenceType is an abstract ReferenceType; only subtypes of it can be used. It is a subtype of HierarchicalReferences.
The semantic is to indicate that References of this type span a non-looping hierarchy.
Starting from Node “A” and only following References of the subtypes of the HasChild ReferenceType it shall never be possible to return to “A”.
But it is allowed that following the References there may be more than one path leading to another Node “B”.

issue 1;
in the sentence "But it is allowed that following the References there may be more than one path leading to another Node “B”.' it is not clear if the term 'References' refers to a HasChild mentioned before or all types references.

issue2:
Although we understand easily that one parent node may have multiple children. The specs doesn't clearly state if it is possible for one given child item to have multiple parents.

I would suggest that the specification clearly states:

• It is possible for one child node to have one or more parent nodes, as far the non-looping rule is preserved

or

• one child node should only point to one single parent node.

whichever is correct.