Adding Additional Map entries to a Wad

How does one go about making additional map entries? I used to just copy pasta lump entries using WinTex. Is there a simple way of accomplishing this feat with Doom Builder or XWE?

tl dr;

Adding MAP01 MAP02 MAP03 to wad file how I do this?

You can merge wads with XWE. DB is also supposed to be able to save maps into a wad with other maps, but I've never tried that myself.

That's sounds practical with XWE, but I have a bunch of individual maps all as MAP01 so would merging them be messy? Or do I just need to mess around with XWE more?

SlumpEd is another editor which is suited nicely for the task.

Simply open the various wads you want to work with. Each one will show up on a separate tab. If you have a specific sequence of maps in mind, then rename the mapxx lump to suit (for example map01 to map05) and then highlight all lumps and copy/paste everything into one wad, until you have one wad with all the maps.

And above all, remember that a map is not just one lump.

Excellent. Thanks.