Transactional Replication With Updateable Subscriptions And Identity Management

Replication Type: Transactional With Updateable Subscriptions
SQL Server Version: SQL Server 2005 Enterprise Edition
Publisher, Subscriber1 and Subscriber2 all on same SQL Server

Problem: I am trying to set up a transactional replication with two updateable subscriptions. All three databases are a carbon copy of each other. Every table to be replicated contains an identity key column. I've been asked to create the replication without assigning separate identity ranges for the publisher and the updateable subscriptions. In other words they want a continous ID range. Can this be done without managing identity ranges programatically outside of SQL Server itself?

Example:

Publisher inserts into table test1 in database1. This creates ID 100 for the record. ID 100 replicates to Subscriber1 (database2) and Subscriber2 (database3).
Subscriber1 and 2 identity seeds are then incremented to ID 100. So far, all three databases have the same identity seed in table test1. Subscriber1 inserts into table test1 in database2. This creates ID 101 for the record. ID 101 is replicated to Subscriber2 (database3) and to the publisher (database1).
Subscriber2 identity seed is then incremented to ID 101. However, the Publisher retains it's original identity seed of 100.
Insert into Publisher table test1 will fail since it will try to insert the identity seed of 101 which is taken.

I have tried identity range management Automatic and Manual. Both seem to have some limitations in managing identity seeds unless different identity ranges are assigned for publisher and subscriber.

Can someone recommend a solution to this problem? Can this be done natively in SQL Server 2005 replication. Or can some recommend another approach to make this work?