Exclude a certain domain from the people picker results

Question

So we have a SharePoint farm that is upon an AD forest, that forest is linked to other forests in a two-way trust.

Then, we have the people picker that is working quite fine and finding every user we try to find, regardless of what domain the user is on.

Now, I need to configure the people picker to find all users from current and future domains in the entirity of the relations BUT one of them. So, it must be a configuration where regardless of what domains, OUs, new or old 2-way trusts are configured, the people picker will find users for all domains BUT one of them.

I've tried to search for an LDAP query that'd do the job to feed to peoplepicker-searchadcustomfilter however could not find it or build it myself. Our AD expert could not get to it too.

I'd rather not use Peoplepicker-searchadforests because later on when they'd add a new domain, someone would have to remember that the people picker needed some configuration. I might be far away when that happens and someone would have to crack his head to find it.

So, from an LDAP Query standpoint, what'd you suggest? Much appreciated.