Contacts and Companies sharing data (and/or importing at the same time)

I’m looking to import about 20,000 companies with their (1-5) contacts. Most of my contacts share contact info (office address/phone, etc.). Is there a way that I can import that all at the same time instead of segregating my company and contact CSV files?

I know it’s just a click of a screen to swap where the info is at, but I’d like for each contact and company to seem “complete”. It’d also be a lot easier to import that shared data with the Company the way my data is set up.