Yes, you can certainly sew panels together, just keep in mind that it won’t look as natural with 2 seams being sewn together. If you would like to purchase these we suggest buying at least 6 panels if you plan on stacking an even amount on each side and opening them up. You can get away with 5 if you truly want to create one solid piece to slide back and forth.
We do have a couple of alternatives that would only necessitate purchasing two panels for the width of your window. These would look a lot more natural and fuller than sewing several panels together to meet the width. This panel comes lined or with a thermal lining. Please see the links below.