Domain Mapping + Multi Domain + redirect?

I have domain mapping and multi domain plugins installed.. I am trying to figure out if I can do the following.

There are two domains.

spgregister.com (primary)
lpregister.com (set up as multi option/private)

lpregister will be used for a subset of sites, so I set up multidomain to allow that to be selected when a new site is created. However, if just the domain name is entered, lpregister.com redirects to the "main site/site 1" of spgregister.com

Since the sub sites using lpregister.com are branded in a specific way, is it possible to set it up if lpregister.com (by itself) is entered, it redirects to a specific sub site (set up to use lpregister.com, such as lpregister.com/welcome) instead of the parent main site spgregister.com?