curl --request POST \
  --url https://services.leadconnectorhq.com/opportunities/{id}/followers \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'Version: <version>' \
  --data '
{
  "followers": [
    "sx6wyHhbFdRXh302Lunr",
    "sx6wyHhbFdRXh302Lunr"
  ]
}
'

{
  "followers": [
    "sx6wyHhbFdRXh302Lunr",
    "sx6wyHhbFdRXh302LLss"
  ],
  "followersAdded": [
    "Mx6wyHhbFdRXh302Luer",
    "Ka6wyHhbFdRXh302LLsAm"
  ]
}