Ok thanks, that helps but it's not quite what I wanted.
I hope this explanation is easy to follow, I've shown a series of screenshots in the atachments. Bearing in mind the client cannot work in source view.
1.jpg is what we have to start.
We want to add a new fact after the first one and end up with 5.jpg and 6.jpg (see below).
So the client adds a line break after the first line and it looks like 2.jpg
But this adds the line break after the start of the second line div as shown in source view 3.jpg
Then when the client uses the "add div" button and adds the class name "content" it adds the new div inside the original second line div as shown in 4.jpg
For the fading jquery script to run through the lines of text in order the source has to be as 6.jpg (couldnt upload 6.jpg because of upload limit so here it is pasted below
<div class="content">
A zebra is white with black stripes, not black with white stripes.</div>
<div class="content">
This is the new fact that is to be added.</div>
<div class="content">
It's impossible to fold any normal piece of paper more than 7 times (try it!)</div>
<div class="content">
On average a four year old asks 437 questions a day.</div>
<div class="content">
It is impossible for most people to lick their own elbow.</div>
<div class="content">
If the client was familiar with html or I thought they could be trained successfully to consistently type in the code in source view then this wouldnt be a problem but this is not the case.
I hope you can follow this!
