In the wiki here it says California doesn't check the "from" name/signature on moped transfer paperwork so you can just put anyone and have them sign. In my case this is on a moped that already had a California plate.
This is wrong. DMV sent me a letter that now I need a bill of sale to show the proper chain of custody. But at least now I have the seller's name.
I don't have bill of sale because my dad found this moped at a garage sale for cheap and the seller was a super-flake. Might be able to still track him down I guess.
Any advice here? I guess I'll update the wiki.