How to configue an Open vSwitch in GNS3 to use a command line when starting up?

Question

In a GNS3 project, how can I edit the startup file of an Open vSwitch so it automatically deletes the bridge 'br0' and creates a new bridge with two ports without using Terminal?

So far, I have used the "Edit config" option to setup an OVS' IP address, netmask and gateway, but haven't managed to use actual Terminal commands in the file.

This is how the startup file is configured so far:

auto eth0
iface eth0 inet static
    address 200.20.225.1
    netmask 255.255.255.0
    gateway 192.168.20.2
    up ovs-vsctl del-br br0
    up ovs-vsctl add-br br0
    up ovs-vsctl add-port br0 eth0
    up ovs-vsctl add-port br0 eth1

With this configuration, when I start the OVS and run ovs-vsctl show, the 'br0' bridge and all the unnecessary ports remain.

I've also tried using "up echo ovs-vsctl...", but to no result.