Shorewall to protect interfaces that are not yet defined

I am planning to use Shorewall to filter traffic that originates from a virtual interface created by OpenVPN (lets call it tap0). If OpenVPN did not successfully create this interface before Shorewall started, but the interface was defined in /etc/shorewall/interfaces, would traffic be filtered if the interface was successfully created later? Would this depend on a script hook, or does Shorewall pre-create rules for interfaces that are defined in the configuration, but do not exist?