Is there a way to install
========= SCRAPER REMOVED AN EMBEDDED LINK HERE ===========
url was:"http://bookmark-merger.sourceforge.net/"
linktext was:"Firefox Bookmarks.html Merger"
====================================
?

Alternatively, is there any other way to combine two bookmarks files into a new one? Thanks

Newer versions of firefox (and iceweasel) no longer read from, nor write to, a"bookmarks.html" file-on-disk by default.
You need to change one pref value (search"browser.places.importBookmarksHTML" in about:config) to force the browser to look for, and import the contents of
a bookmarks.html file... and change a separate pref value (keyname browser.bookmarks.autoExportHTML ) to force the browser to create/maintain a bookmarks.html file in addition
to (just) storing the bookmarks data within"places.html" sqlite datafile.

If bookmarks.html exists and the browser prefs are set to look for / import such, while the browser is not running
you can freely edit (cut/copy/paste/merge) the file. If the browser is NOT set to use/maintain a bookmarks.html file...

...you can"import" be installing"sqlite manager" browser extension, then import the contents of the foreign
(pathed outside your browser profile directory) into the current (pathed in your profile dir)"places.sqlite"

For the sake of completeness, in response to"is there any other way to combine..."
I'll mention that the FEBE browser extension reputedly can (I've not tried to) handle the chore of importing bookmark file(s).

note: When you export to bookmarks.html file, any"tags" are not preserved (because bookmark.html datafile structure has no concept of tags)