^^ I get what you are saying, but if she is afraid/feeling insecure, I don't think the answer is to not help out. That makes you less valuable. If I thought my job was in jeopardy, I would be showing how much of a team player I was.
But, I agree with NetG and RileyB. I'm sure I see what the issue is
When they got rid of our admin, we all had to split her functions. No one thought twice about it. And yes, I work in IT. And 80% of those people did go on to loose their jobs
I also like the suggestion of coming up with a proposal for a long term solution. Very nice idea (careerwise)