Freight Carriers - Multiple Sites/Addresses

Hi,

We have freight carriers will multiple sites/addresses. When i try to define the sites/addresses and assign to the inventory orgs i observe that i can assign only one site to my inventory orgs. For e.g. for a carrier i have two sites/address say S1 & S2. If i assign S1 to org A, i cannot assign S2 to org A. Infact the org A doesn't show on the organization assignment form. This issue is with sites/address only. I am able to assign my service levels to all orgs. Is this a standard behavior? Where is the freight carrier site/address used in the shipping