Hi Hanley,
Method already sets multiple contact Record IDs to one customer Record ID (If you go to the customer tab and view an existing customer, there's a tab there where you can assign contacts to that customer); but you cannot have multiple customers to one contact.
That being said, solutions to what you are looking for are possible but are very complex and time consuming as you would need to customize your contacts table, and then customize every single screen that uses your customers and contacts, as well as the reports that use them. You would then need to change how the grids for those screens would work. The simplest thing you can do is to add tags to your contacts as the customer names, but it won't be as dynamic; and you will need to change it manually everytime you change something into a customer and you will still have to change the grid filtering.
In conclusion, a simple solution to connect multiple customer record IDs to one contact record ID is not possible. You can always contact a Method customization consultant and they can do it for you if it's absolutely necessary.
Let me know if I answered your question or need more clarification.
Thanks,
Marwan