
I was a sponsor in one of numerous districts for LaZy and moved several times to accomodate other guilds, that even after appearing in the district long after I'd been camping and annoucing there, seemed to feel a strong emotional attachment to the particular district

Keep it flexible. If it's like last year there will be more than enough districts for all the sponsors.
As far as "this district is only to be used by such and such" - good luck with that... rather absurd IMO.