21.20.7. For the purpose of determining if two corporations are associated with each other at any time by reason of both of the corporations being controlled at that time, directly or indirectly, by the same group of persons that includes one or more specified entities, neither the shares of the capital stock of those corporations owned by any specified entity that is a member of the group of persons, nor any right referred to in section 21.20.4 held by any specified entity that is a member of the group of persons, shall be taken into account at that time.
However, where a specified entity is a member at a particular time of a group of persons that controls several corporations, and, at that time, the specified entity acts in concert with one or more members of the group of persons to control those corporations, the specified entity is deemed, for the purposes of the first paragraph in respect of those corporations, not to be a specified entity at that time.