Please help for lease function

[Krzysztof Mościcki]

Greetings,

I'm testing patchset and configuration from webpage
http://www.miquels.cistron.nl/isc-dhcpd/ and there's everything I need
except one thing. I need DHCP server to staticly assign IP address
based on switch (from remote-id) and port number (from circuit-id).
Unfortunately there's a problem. If another device (different mac) is
plugged to previously occupied port and old lease is still valid,
there's "no free leases" message for new device. Therefore I'd like to
modify dhcp server in a way, that would allow new lease in case of
static port assignment. Not knowing dhcp server code, I'm having hard
time implementing the modification. I'd be grateful for a hint. Where
should I start to achieve my goal? Options that come to mind are to
disable adding static ip assignments to lease file OR to disable MAC and
UID lease check. I'd be gratefull for any sugestions in that matter.

-- 
Krzysztof Mościcki