How to combine two paths in Illustrator

Question

Is it possible to combine an open path and a closed path in Illustrator?

I want to take these two paths:

And combine them to make a box like this, except I don't want the points of the diamond-shaped path to extend past the left and right side of the other path:

Answer 1

No. It's not possible. Each anchor point in Illustrator can only contain and in and out path. You can not have 3 paths using the same anchor point.

You could expand the strokes and then combine shapes, but you can't combine strokes.

A better method would be to draw the outer shape as one path, then inner paths separately rather than trying to combine paths to create the outer shape....

Answer 2

There are ways to combine paths but, in this case, you can't make that one path and retain it's appearance.

You have a couple of options. Your solution is really going to depend on how you want to style this in the end.

1. Adjust the lower, open path (defining the left and right "side" of your box) to align with the corners of the upper, closed path (the top).

2. Redraw (or cut up and recombine your shape) so it's a hexagon with the v as a stand alone path defining the top edge. So this would be your base shape ...