Getting "wrong" DNS-Server on DHCPINFORM

[Humpty Dumpty]

Greetings!
Running dhcpd 3.0.3 and dhcpd.conf looks something like this:

#### dhcpd.conf
allow unknown-clients;
ddns-update-style ad-hoc;
authoritative;
...
subnet 10.0.0.0 netmask 255.0.0.0 {
range 10.0.10.1 10.0.10.254;
option subnet-mask 255.0.0.0;
option broadcast-address 10.255.255.255;
option domain-name "my.domain.com";
one-lease-per-client on;
default-lease-time 14400;
max-lease-time 14401;
option ip-forwarding off;
option time-offset -18000;
option time-offset -18000;
option routers 10.10.10.10;
option domain-name-servers 10.0.0.9;
ddns-updates on;
ddns-update-style ad-hoc;
ddns-domainname "my.domain.com";
use-host-decl-names on;
}

group { update-static-leases on;

####### Host MAC Adressen

host voyager { hardware ethernet 00:50:fc:72:9a:54; fixed-address 10.0.0.2;
option domain-name-servers 10.0.0.1; option routers 10.0.0.1; ddns-hostname
voyager; }
## lot of host entries
....
####

What I want is, that known hosts geht the options (especially DNS-Servers)
from their host-section and unknown hosts get that one, from the
subnet-section (i.e. 10.0.0.9).
This works just fine for leases. But a lot of
windows-clients which are known hosts (e.g. 10.0.0.2) sometimes send
DHCPINFORM packets and receive ACKs with options from the subnet-section (
i.e. domain-name-server 10.0.0.9). The windows-clients then change their DNS
to that value from the subnet-section
(interestingly they don't change their gateway-value even though the
ACK-package gives them the
10.10.10.10-value).

Now the question is: How could I get dhcpd to send the options from the
according host-section or just ignore DHCPINFORM packets?