i have big house with three stoy, and i have the 1000 mbps internet (fiber optic) and from the router i have wall cables to every room, and i have apple 3 airpot extreme connected throw gigabit switch (conected to the router) and i want to add add more routers. my question is can i add another company routers and still het roaming wifi with the airport extreme or do i have to replace the all routers ? and what is the best system for me.