Multiple network interfaces on Mac OSX

Hi Folks, I'd like to create instances that have multiple interfaces. One interface, connects to a shared interface out to the Internet, the other instance connected to a private bridge on my MBP.

I found some posts online and it looks like folks have done it before, but it's not working for me. Here's have I've done:

sudo ifconfig bridge200 create
sudo ifconfig bridge200 inet 192.168.10.1 netmask 255.255.255.0
sudo ifconfig bridge200 up

Followed by:

multipass launch -n first-vm --cpus 4 --disk 20G --memory 8G --cloud-init cloud-init.yaml \
--network en0 \
--network name=bridge200,mode=manual

When I do this, I get the following error:

launch failed: Invalid arguments supplied
Invalid network options supplied

I can see the bridge on my laptop:

bridge200: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULT ICAST> mtu 1500
options=63<RXCSUM,TXCSUM,TSO4,TSO6>
ether XX:XX:XX:XX:XX:XX
inet 192.168.10.1 netmask 0xffffff00 broadcast 192.168.10.255
Configuration:
id 0:0:0:0:0:0 priority 0 hellotime 0 fwddelay 0
maxage 0 holdcnt 0 proto stp maxaddr 100 timeout 1200
root id 0:0:0:0:0:0 priority 0 ifcost 0 port 0
ipfilter disabled flags 0x0
media: <unknown type>
status: inactive

However, Multipass networks does not see the bridge:

❯ mp networks
Name Type Description
en0 wifi Wi-Fi
en4 ethernet Ethernet Adapter (en4)
en5 ethernet Ethernet Adapter (en5)
en6 ethernet Ethernet Adapter (en6)
en7 usb USB 10/100/1000 LAN

Greatly appreciate any pointers!

Dave.