i never used avlinux, so don't know it well enough to give any advice.
which grub avlinux uses, grub 1 (grub legacy) or grub 2? i'll suppose it uses grub2.
being a debian-based distro, it shoud have one or two commands (or both of them):
the command scans hard disk(s) for any oses installed on it, and adds those found to grub.cfg file (if you use grub2).
try to run one of these commands, as root. it should find your solydx and include it in grub2 startup menu.
just two notes.
1. it's strange that solydx wasn't already included in avlinux's menu. any self-respecting distro runs update-grub(2) command automatically as one of the final steps during installation, so all pre-existing oses are ready to be used on the first launch of the freshly installed distro.
2. personally, i hate grub2. still don't understand, why it was introduced. why it exists. grub1 is far better than grub2. and it's extremely easy to manually add grub1 (grub legacy) to ANY grub2-only distro. grub1 permits to have a total control over the entire boot process. instead of grub2 madness.
in all grub2-only distros i just "kill" it, replacing it with grub1. solydxk included
. to have a clear and simple way to control the boot. instead of wasting time struggling against grub2.
sorry for the 2nd note. just run update-grub(2) in the os you're booting in by default. hope this helps.