@engineer,
Can a candidate release his/her candidates on the first ballot at the convention? I don't know if there is any provision for that. In a sizable number of states-I think a third or so-the state laws says that any delegate pledged to vote for a candidate in a primary held in that state must vote for that candidate, at least on the first ballot. As to what the rules of the Democratic Party itself are about that for states that don't have that law, I don't know. I don't recall any candidate releasing their first ballot delegates to any other candidate, but I might be wrong.
Even if it is possible-and it might be-how would it look? Two candidates battle each other for a year, the underdog gets close, the favorite has to withdraw because of an FBI indictment pursuit, (actually she wouldn't necessarily have to do that, it would be up to her), and instead of giving the nomination to the underdog who came close, the favorite releases her delegates and some candidate who wasn't even running but was in tight with the Democratic leadership gets it. Or worse, it might not be possible for the candidate to release her delegates but the Democratic Party changes the bylaws at the convention to make it possible, then those newly freed delegates get together to screw over the guy who fought for a year and came close.
The voters might wonder why the hell they even bother watching the democratic process if the party is going to throw it out the window and put in the party leaders' favorite anyway.