If I am understanding your setup correctly, the static ip's should just need to be on the same network id as the router. Find out what the ip of the router is. Router documentation should say what the default ip is. If not, the simplest way would be go to a command prompt and type in "ipconfig"
The default gateway address is your router. In most cases, you should have a 192.168.x.x address, if not, specify what it is. The first 3 sections of the ip will be the network id, make sure that those numbers on your static ip's match the numbers on the router. For example if the default gateway is 192.168.1.1, then make sure the static ip addresses are 192.168.1.x Then assign x a static value(between 2-254). If the other 3 get their address through dhcp, make sure the static addresses are outside of the dhcp pool.