adding an AAD security group to site collection administrator using power automate

hi , thank you for your answer, yes this format worked at the end but you can add them in one HTTP request no need for 2:

{

  "type": "OpenApiConnection",

  "inputs": {

    "parameters": {

      "dataset": "https://.sharepoint.com/",

      "parameters/method": "POST",

      "parameters/uri": "_api/web/siteusers",

      "parameters/headers": {

        "content-type": "application/json;odata=nometadata",

        "accept": "application/json;odata=nometadata"

      },

      "parameters/body": "{\n    \"LoginName\": \"c:0t.c|tenant|a1e0c1af-...\",\n    \"IsSiteAdmin\": true\n}"

    },

    "host": {

      "apiId": "/providers/Microsoft.PowerApps/apis/shared_sharepointonline",

      "connection": "shared_sharepointonline",

      "operationId": "HttpRequest"

    }

  },

  "runAfter": {

    "Compose": [

      "Succeeded"

    ]

  }

}