You may need to use a data enrichment tool like Leadspace or something similar. This would give you a "Domestic Ultimate" and "Global Ultimate" company value for each account, contact, and lead. You could use the Global Ultimate (or highest parent company) value to include all subsidiaries of a company.
I have attempted to use smart campaigns in the past to manually normalize company names and match with parent accounts to include all subsidiaries. It takes a lot of time and becomes very difficult to manage without a data normalization tool.