I'm not part of the management, so can't speak for them, but I'm not concerned at all -- pretty sure it's all worked out.
If that really is a rule, it doesn't make a lot of sense, does it? It seems more logical to encourage all varieties of corps at every level -- makes everyone stronger.
I marched in the alumni show in the '06 and '07 Bridgemen. It would be pretty funny if that's what qualifies us to go to DCA!
I believe it's about the status of the corps. I perform with a mini-corps that does not use the word alumni in its name. There are many members of the group (actually almost all of them) are in other alumni corps. My group is considered an alumni corps because we are a year round organization not one that just gets together to play at DCA. We actually do parades albeit on a flat-bed, but hey it works for us as well as exhibitions at both DCI and DCA shows.
I think that whether it makes sense or not, the rule it the rule and few groups that I know of have had a problem with it. I believe its intent is to keep out groups of professionals that just assemble themselves together and come to DCA with no affiliation to drum corps and beat the pants off everybody.