Is there any way to get all of the children of a parent row? The only method that I see, is to grab all of the rows and look at the parentId's assigned to the children.
(For what it is worth, I am using the javascript api)
I don't believe it's currently possible to explicitly request all child rows of a specified row, using the SmartSheet API.
As you've described in your post, you'd need to use the Get Sheet operation to get the list of all rows in the sheet, then look for row objects in that result set where parentId matches the id of the parent row you're interested in.