Hi, to get all the children and store them, you need an array. An array acts like a list of game objects (or other things).
You will need to create a loop using playmaker.
You will need to use the action "Get Child Number". Number 0 will be the first child. So start with an Int Variable (maybe called myChildNumber). Set it to 0. Then add 1 each time after you finish getting the child and saving it to an array.
Each time check if the child is null. (Because once you are done getting all the child, the last one will be null). When Get Child Number returns null, then you can stop adding gameobjects to your array.
Once you have all of them in array. You can easily count up or down the chain to get any link you want.