So, this is perfect for me.  I JUST finished a jam, but realized after submission that the game was 1) unbeatable due to a >= being a ==, and 2) generally buggy.  I already fixed a FEW of the issues before I found this jam (which is how I know about the bug), but will wait until it starts to really work on improving it!

The one question I have is about the devlog.  the Jam I submitted the game I want to improve on was for GBJam13 (Link here).  In that jam, we are not allowed to make changes to the game/submission until the voting period is over (Which is on October 6th).  Can I make a Different project and merge it with the existing after the jam? Would that mess up the voting/visibility of THIS jam?  Like, Can I have a private submission that I make the changes to?  i don't want to have 2 versions of the game each in their own page, instead I want to offer the 'jam' version and later add a 1.x version after I make improvements.  

Any idea on how I can make this work for this jam?

from what I read and understood, as long as the project has already been in development prior to the start of the competition it's eligible. Any form of proof of it existing should work, but making a dev log is easy after you navigate the ui a bit. It took me awhile. Hope my answer helps or gets corrected by a more informed person. Best of fun. 

Once there is some sort of proof that it's not a newly created game... You should be fine. If it is found that you broke the rules, your entry will be disqualified. In your case, I see no issues with you creating a new page just for this jam. But just in case, link it to the real page.