Merging multiple feature modules
Sometimes the best way to merge/split features is to edit the module code directly. It's pretty straightforward where everything is laid out in a module created by Features. And it's a great way to start learning module development (if you're new to it). Just start at the *.info file - that's where Features describes all the various things it manages in the module. Then you can pretty easily find those things in the *.module file and other *.inc files. Just clone the whole module, rename it and all the files, search and replace all occurrences of the name in the code, then remove the stuff you don't want in each.