Redundant Azure ExpressRoute Connection on v4 API

Do a post to `/fabric/v4/connections bulk instead`
Then include both connections in the payload:
{
"data": [
{
}
]
}

I thought I could edit previous post...
Your payload should look something like this:
{
"data": [
{
...
"redundancy": {
"group": "757efa1e-ceb8-423c-8730-d85cf82c46c3",
"priority": "PRIMARY"
}
...
},
{
...
"redundancy": {
"group": "757efa1e-ceb8-423c-8730-d85cf82c46c3",
"priority": "SECONDARY"
}
...
}
]
}

Note that for the "group" I have generated a random uuid and assigned it for both.
This worked well for me.