Generally no, all communication between husband and wife is what is called Spousal Privilege that states one may not force a wife to testify against her spouse. However, the Spousal Privilege may be breached by an exception to the rule.
A parent company is a company that owns enough voting stock in another firm (subsidiary) to control management and operations by influencing or electing its board of directors. A parent company could simply be a company that wholly owns another company.
A holding company is an entity formed to buy and hold the majority of stock of other companies; a subsidiary is a business whose majority of stock is owned by a holding company.