There are three basic things that can occur, all depending on what you purchase and how you purchase.
2. Add-On Contracts, the smaller unbrella under the big unbrella. You only have one membership number, but several Add-on contracts
You purchase a June OKW contract, and later add-on a BWV contract, and later an SSR contract. You now have 3-contracts, but only one Membership Number. These all have the same base contract number but with different contract extensions. Example: 12345.000, 12345.001, and 12345.002.