Reseller server(s) via client interface (main host server should not be visible)

hi, I'm trying to get the interface to work seamlessly between clients, resellers and myself/server. Apologies in advance if this is obvious to the more experienced members here, but I'm unable to see why this is not working as I'd like it to.

I have a single host server, my.srv.net and several resellers: my.resel1.com, my.resel2.com, then I have several clients: my.client1.com, my.client2.com, my.client3.com, etc. etc. Almost everything seems to be working smoothly, client accounts, websites, email, (much kudos for great code). The singular issue that I have is that when a client, or a reseller, is using the ispConfig interface, (at the website or email interface screens), they only have the single my.srv.net Server to choose from the "available Servers" popup.

On the one hand this makes sense, it's the only "real" server that exists after all. On the other hand, it's very wrong, as the client2.com needs to be able to select only a my.resel2.com (for example) Server. Of course the Server which is available for the client to choose is whichever server belongs to the relevant reseller to whom the client belongs.

Code:

my.srv.net  <- clients should *not* see this server
my.resel1.com  my.resel2.com
...            my.client2.com <- client2 should only see the my.resel2.com server option.

I'm probably just missing the obvious way for a reseller to say "use this (reseller) server for all my clients", or similar.
I hope this makes sense and welcome any helpful suggestions here.