You are asking a how-to question and getting how-to answers, but I am in the camp with @Nathan Gesner.

Hi Community, 
Requesting help form all East Bay, California builder/investors experienced with an ADU (Additional dwelling Unit) build.  I am self-managing my ADU build in Oakland, CA and have come across a few snag...

I am thinking instead of making the tenant sign all of the paper with new LLC for next three months, I should make her sign an addendum that states - She acknowledges that original lease was signed with KY LLC ( of course we will insert the real LLC name) and now the property is under new LLC.. so nothing changes,  all contracts , obligation stays the same as with the old LLC.Two questions:1.

Reach out if you have any questions!

A couple of things here and there are no big deal, but if you can't even take the time to clean up your question, why would you get the best answers?

Thanks for the question.

I have the following questions: Has anyone done this before?

Software is a common question on BiggerPockets.

So my question is: Could anything change with the mortgage if the LLC is under new ownership (other than a bank potentially calling the loan due which is typically in any 30 year fixed) Then the icing on the cake: Obviously I'm attempting to pull this off right now lol.

I suggest that you start a new post in the most appropriate forum so that you get the greatest visibility and most beneficial feedback, your question may get lost here.