ToolTips are a Component; they are not "added" to a Form's ControlsCollection, or to Container Controls' ControlsCollection in a Form, in the Designer.cs file of a Form.
You can build a collection of ToolTips like this:
public List<ToolTip> tTipList = new List<ToolTip>();
tTipList = this.components.Components.OfType<tooltip>().ToList();</tooltip>
Rather weird syntax, imho.