is it possible to anchor a control to another control?

I extensively use TableLayoutPanels and FlowLayoutPanels to accomplish this. For you specific circumstance I would use a TableLayoutPanel with three columns and a row for each TextBox.

Column 1: Auto-width, contains Labels all with AutoSize = True.
Column 2: 100% width, contains TextBoxes all with Anchor = Left, Right.
Column 3: Auto-width, contains the Button in the appropriate row.

Next, I set all text boxes, except for the one next to the button, ColumnSpan = 2. Then just put the TableLayoutPanel in the SplitPanel and set Dock = Fill.