custom diff - text file diary entries

Problem: Separate text file diary entries, committed in separate repos, cause merge clash when pushed to central repo, since git thinks the two entries are a single conflicting entry (since they begin at the same location in the same file).

What we need is two diary entries automatically detected and inserted into the one file, one above the other (ordering is not so important).

Detail: I have a repo of diary text files; each diary entry is separated by three blank lines and has an asterisked + dated header, and a body. Here is an example diary file contents: ---- *20101230 by sarah, @~3:00pm Phoned James and asked why he took so long shopping. He said he had planned a one day trip, but got lost in Bunnings. I told him 'yeah sure, like I believe that'. I asked him what he got.

This is the list he told me:
 - pliers
 - hammer
 - nails

*20101229 by james Today I went shopping. Bought some eggs. ----

Each new diary entry gets added in the appropriate diary file in reverse chronological order.

james, sarah and others each share a few diary files (different diaries have different purposes).

The problem is: james and sarah, each in their own clone of the central repo; they each add a new diary entry to the same file, then commit, then push;

the second person to push will fail, since each new diary entry occurs in the same location, the top of the file; this requires a pull: result is git gives me the following (james pushed 2nd) extract:

<<<<<<< HEAD *20101231 by james I took a day off today. Didn't do much at all. ======= *20101231 by sarah James told me this morning he was taking a day off, so bugger it, I decided to take a day off too.

I switched on the answering machine.

Desired outcome: Two new diary entries - two separate insertions into the text file, not the conflict.

Is there an easy way I can automate this diary entry merging, so my users don't have to manually resolve the conflict?

Please note: SOMETIMES, one user will go and correct spelling and/ or grammar fixes in another person's diary entry, or in their own older diary entry - this is quite common.

TIA Zen