Rather than adding the sales page and order page objects separately on the canvas, we can link them together to become one object.
Add a sales page object onto the canvas.
Double-click on the sales page object and toggle the single page toggle to the right.
Update the page type options of 1 step or 2 step. And, a toggle the order bump option if you want. Then click save.
Now the sales and order page is one object.
Notes
Page Type - 1 step
Page Type - 2 step