Having used Access quite a bit, I think I know what you are asking, and the answer is, "There isn't one". You cannot insert an already created form as a control on another form. However, you can use a PictureBox control as a container for other controls, in effect making it a sub-form. You can have several Picture boxes, each with their own set of controls, and hide and unhide them dynamically, allowing you to, in effect, display several different "sub-forms" in the same area, based on run-time logic.
Also look into using the Tab control, which allows you to create sets of controls on each tab, and then switch which tab is visible at any moment, just as you would do manually with multiple Picture Boxes.
But it really depends on what you are wanting to do. If you just want to display a grid of data, use a DataGrid control and a Data control to bind to.
If this doesn't help, let us know what it is you want to accomplish, and we can give you some ideas on how to accomplish it.
Happy Thanksgiving!