>>>2. The local sites keep a copy of the master database, which is updated
>>>periodically with standard replication.
>>
>> This is where I hit my first "bump in the road". The client wants to use
>> the FREE version of MSDE or MySQL. Neither version offers 2-way
>> replication.
>
>I'm not aware that there is any two-way replication solution for MySQL,
>regardless of free vs. commercial. Can you cite a reference?

According to the manual for MySQL 5.0.19 (NOT cluster) on the
dev.mysql.com site, a given server can have one master and multiple
slaves. You are allowed to connect them in a circular setup. There
is little provision for resolving conflicts in near-simulataneous
updates. This is probably not acceptable for what the original
poster wants. But it is arguably two-way replication, particularly
with the setup on two servers.

The server variables auto_increment_increment and auto_increment_offset
are provided to deal with the assignment of auto_increment values.
From the descriptions I see, it looks like they work with multiple
masters, but I don't know how you have multiple masters. The idea
is that each server assigns its own set of numbers, e.g. with 10
servers, one server assigns 11, 21, 31, 41, ... and another server
assigns 13, 23, 33, 43, ... .

Gordon L. Burditt