Home Network :: Add Third Wireless Router To Equation?

We have adsl and the current system setup is as follows:

I have a plain dlink adsl modem connected as my starting point in bridged mode. This is to allow different users to connect with their own adsl isp user accounts.Then after that I have a linksys wireless router that is connected to it via a switch on an available port on both the switch and linksys router.We can all access the wireless fine,access the wired PCs, printers, etc.My problem is I want to add a third wireless router to the equation that will dial a single account and will be used primarily for our mobile phones and guests. So, always on, wireless connection to an always connected adsl line.

I got everything working up to a point.When I connected my new wireless router via its wan port,it worked as expected.I had enabled DHCP on it and also assigned a static ip for itself in the same class as the rest of the network. Any device connected to that wireless network can access the internet and the other devices connected to the same network. However, when I try to access the rest of the network,I get a host unreachable error on ping and when trying to access it directly via ip addresses.I then disabled the dhcp on it and thought that my primary dhcp (the linksys) would assign the devices, but that also did not work. I am sure that if I had connected the router via one of its normal lan ports it could have worked, but then I can't set it up for PPPoE.