Junction all your GFs to whoever is in your main party. There is a swap command in one of the menus if you are changing characters out, or have to use specific characters at certain times. I forget exactly what it's called, but it swaps everything cleanly; GFs, magic, junctions. You want to have all of your GF's in every battle, leveling up and gaining AP for abilities.
The first time, I had trouble, even with summoned help. I played some Dark Souls last month with a new character, and while it took me a few tries to get past those damn dogs, it's a pretty simple fight. Kill dogs real fast, run up stairs, let him follow you off the ledge and hit him when he falls.