Get Active Sibling Index - Use this script to create the extension method GetActiveSiblingIndex which allows you to find the sibling index whilst ignoring inactive siblings. Useful for animations that are meant to run in sequence, but have unusual delays caused by inactive sibling changing the numbers

GetActiveSiblingIndexScript.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public static class GetActiveSiblingIndexScript {
    public static int GetActiveSiblingIndex(this Transform transform)
    {
        int index = 0;

        for (int i = 0; i < transform.parent.childCount; i++)
        {
            Transform nextChild = transform.parent.GetChild(i);

            if (!nextChild.gameObject.activeSelf)
                continue;
            else if (nextChild == transform)
                return index;
            else
                index++;

        }

        return index;
    }

}