Replication Using SQL Server 2000 - Error Number: -2147200976)

I have few databases with SAME database structure in
SQL Server 2000 in different locations.  Data will be
updated in different places with different sets of
data.   Basically, i need to synchronize the data
especially to the headquarters database   periodically
(may be everyday at night).
 
DB : SQL Server 2000
OS : Both are running on Windows XP for testing
purposes.
Situation : Now i have 2 database from 2 different
estates. Now, need to be synched into 1.
 
Have 2 publisher namely TH1, TH2
1 subscriber : THFinal
 
I've created 2 individual publications using "Create 
Publication" and published database namely TH1 and
TH2.
Publication type : Merge publication
 
Default table article properties setting are as
follows :
a. When merging from different sources : "Treate
changes to the same column as a conflict (changes to 
different columns in the same row will be merged)".
 
Snapshot
i Choose "DELETE DATA IN THE EXISTING TABLE that
matches the ROW FILTER statement".
 
Resolver :
I checked "yes" for  - Allow Subscribers to resolve
conflicts interactively during on-demand
synchronizations".
 
Now, when i sync the TH1, all the records from TH1
goes to the subscriber database "THFinal".
When i sync the TH2, all the records which was 
synched earlier (from  TH1) being DELETED. and  all
the records from TH2 goes to the subscriber database
"THFinal".
 
Basically, i WANT to retain the ALL THE data from in
"THFinal" which came from TH1 database since the
primary key is different. Also, all the database
contains running no (Identity increment = 1)  .
 
Identity : Yes (Not For Replication) (Identit  seed=1)
 

===================================================
PROBLEM : 1ST (TH1) database can be synched. when
I try to replicate the 2nd (TH2) database, the 
following   ERROR displayed :  The process could not
drop one or more tables  because  the tables are being
used by other publications.
 
The process could not drop one or more tables because
the tables are being used by other publications.
(Source: Merge Replication Provider (Agent); Error
number: -2147200976)

Thanks in Advance

Reagards
Ihsan