hello,
do you want to limit how many ip addresses and know who's using a particular ip address? is that the way you intend to use dhcp?
i see no problem with your picture… but single mac address for three different ip addresses? why not? do you have an isp(internet service provider) that specifies to know their internet subscriber's mac address?
try to set your lan interface with a specific ip address(which is the gateway of course) and then when asked if you want to enable the dhcp server on the lan interface, choose y(yes). then specify the subnet and the range...
based on my experience on pfsense, i would advice you not to use wireless routers as access points and clients if you don't have extensive knowledge or basic networking knowledge because it is quite tedious to configure such items... access-points/bridges are much preferable.
i hope this might be of help... :)