The solution I suggest is to use a third party extension manager like the one from DMXZone: http://www.dmxzone.com/go/22670/dmxzone-extension-manager-for-dreamweaver/
Check this rice cooker guide
It is free and will work with CC 2015
Was having a similar problem with my DW CC 2015. I've just installed the extension manager from DMXZone and it works with your extensions. Thanks.