This is making my brain hurt already!! I've already used the downloaded .iso to install Manjaro (Fringilla) on an old laptop - in that case I just created brand new partition in fdisk and then let Calamares do its thing.
Now I'm trying to install the same image on my existing Fedora system. I have 3 HDDs - one for data, one for music, and one current system drive, an SSD which hosts Fedora on MBR partition using grub2.
Going through the install screen with Calamares, I get to select install destination, and the gui chooses for me but defaults to the wrong disk. At this screen is the option to "install alongside" but since this defaults to an unwanted location I select the desired location using the dropdown (the SSD which currently has a grub partition and the rest is a single LV ext4 containing the Fedora installation). I cannot then proceed with the installation. Even if I choose to manually edit the partition - by shrinking the LV, all I get is a blank area of free space. The "next" option just does not become enabled.