Hello. When bridging, tap and the interface a bind toghether under ONE IP. So, you can use only one IP pool.
/etc/rc.conf
cloned_interfaces="bridge0 tap0"
autobridge_interfaces="bridge0"
autobridge_bridge0="tap0 em0"
ifconfig_bridge0="inet 10.10.128.1 netmask 255.255.255.248"
Then in server.conf use:
local 10.10.128.1
server-bridge 10.10.128.1 255.255.255.248 10.10.128.2 10.10.128.7
Of course you may have IP conflicts with local computers, which you have to handle by expanding IP pool.
The purpose of bridge is to all clients have the same IP as the local LAN computers, mainly used for legacy protocols. If you can - use routing method.