Extending WiFi range with a 8800nl

[itslovelybythesea]

I have an 8800nl that we are using to broadcast two SSID's in a home, one for the use of the kids and one for adults. However, the home is large and the router is situated in one corner of the building so the signal is very weak at the opposite end of the home. Situating the router more centrally is not possible. The adults network is unrestricted, but the network which the kids have access to has MAC address filtering restrictions, time schedules, OpenDNS content filtering etc..

Is there a way, or what product could I get, to extend the range whilst routing all traffic through the MAC/time restrictions which are on the primary router? Running an Ethernet cable to connect two devices would be relatively easy. I've looked into wireless repeaters, but some suggestions have been that as the repeater is connected to the primary router via its own MAC address, the filtering is therefore lost when connecting through a repeater and the network is effectively unrestricted.

Any help gratefully received!