IFRS 10 supersedes IAS 27 Consolidated and Separate Financial Statements and SIC-12
Consolidation—Special Purpose Entities and is effective for annual periods beginning
on or after 1 January 2013.
IFRS 10 Consolidated Financial Statements establishes principles for the presentation
and preparation of consolidated financial statements when an entity controls
one or more other entities.
Therefore it is not possible that two parents establish the principle of "control" on the same entity.