This just keeps getting more and more difficult...

If it was simply a matter of choosing wether or not I stay in my current job or go back to my old job, I think the decision is getting clearer and clearer to me. Last week, though, something came up.

Here's the story:
My current job (Job B) is only a temporary position. It was only supposed to be one year. My old job (Job A) gave me a one year leave to take the position at Job B. This was difficult for my Job A manager because staffing is difficult enough without losing a full-timer for a year. So the leave was good for one year and one year only.
Now, just as I had hoped, Job B has the opportunity to become permanent. BUT, the position has to be approved for the new budget - which doesn't come through until (probably) the end of March. Then the position has to be posted for a certain period of time which I have to apply for and then, to follow protocol, most likely won't officially start until July. But I can't count on the permanent position until the posting is actually up.
Problem 1: I'm supposed to back to Job A on April 1st because that's when my year is up. If I want to stay in Job B until the permanent position starts, I'll need an extension on my leave from Job A. I already know my old boss doesn't want to do that.
Problem 2: I could just quit my position at Job A, stay in my temp position until the end of June, then start the permanent position in July. However, I'm pretty sure I lose out on something if I leave my permanent full-time position for 3 months.
Problem 3: I have to tell my boss from Job A whether I'm coming back or not before the posting of the permanent position at Job B. I can't take the chance that I'll be out of a permanent, full-time job no matter how small that chance is.

Is everything clear? I have to ask for an extension on my leave or go back to Job A for 3 months.
Problem 4: Going back to Job A from April to June is a very very bad time to be leaving Job B. A lot of the work that I've been doing the past 4 months has a great deal of impact on what's happening between April and June. Disappearing would not be good at this time.

I have to win the lottery soon...