User login to base on the URL of a multi-band account

Hi,

We have multiple brands on Zendesk.  For example support.product.ABC.com and support.productXYZ.com are two different products.   

When a user logs in to our portal at support.productABC.com he is directed to the default brand support.productXYZ.com, and only sees the selections of the default brand.  The selections for prodcutXYZ are different.  Therefore the user cannot select any related drop-down information for productABC.    

What we want Zendesk to do:

A user that logs in support.prodcutABC.com to get the selections/drop-downs for that brand, not the default brand.   What we ask is that a user would go the brand that he logs in, based on the URL.

Thanks.