Situation:

(X) is a subsidiary of foreign parent (Y). The subsidiary (X) was sold 100% ownership to and became subsidiary of US Entity (A). In addition, US Entity (A) is subsidiary of foreign parent (B).

The operations of subsidiary (X) and Federal ID will continue with old name and EIN.

Pl advise whether to file separate federal tax returns for (X) and (A) for twelve months or to file two short period tax returns for subsidiary (X).

What are the alternatives, if the subsidiary (X) files consolidated tax return with (A).