I have a web generated laser cut box file and loaded it into inkscape. In an attempt to edit the box by adding shape but the union isn't working the way I want. The box is made of bunch of segments. So I did "combine" then stroke to path...then attempt to union with a shape...let's say it's the circle. But it's not working out. What's going on here? What do I need to do to make the box file a complete path to union with the circle? It's so frustrating...i've spent hours trying to make it work. Thanks!

I wouldn't use stroke to Path... At best that will likely cut the profile twice.

I'd combine the paths of the original tabbed shape, then merge the many duplicate nodes, and then add the new shape to the profile.

Oh wow thank you!! Yes, it worked. Thanks so much for taking the time to show me. I learned something new today. Thanks for the link to the Inkscape manual as well, I will definitely look through it. Thanks again!