Netflow for remote cisco 881 routers


I'm trying to get the bandwidth utilization of remote users. The remote users are connecting via their Cisco 881s with a DMVPN set up to 2, headend routers. We are going to have a 250 remote users, using Cisco 881s from home. We would like to be able to monitor how much of the headend router's bandwidth is being used by each remote user. I've entered the headend nodes on SolarWinds and enabled netflow on the devices and see the devices under the NetFlow>End Points but, don't see much in the way of individual users(881s). There are only about 12 in production at the moment and maybe I won't really notice until more are online but, is there anything else I must do to monitor their bandwidth use? Perhaps add the individual 881s to SolarWinds? I was thinking that by enabling NetFlow on the headends, I would be able to see the bandwidth utilization of the remote 881s.

Thanks, Pat.