No, there are no out-of-partition rows. Few more details about the setup I
have:

- filtering is done by "fake" HOST_NAME();
- 2 push subscriptions on MS SQL Server 2005 Express machines
(9.00.2047.00), 1 publisher on MS SQL Server 2005 Standard (9.00.1399.06);
- rows are only inserted;
- 2 MS Active Directory users in Users group: one for snapshot and the other
for all merge agents, both sysadmins on the publisher and one of them
sysadmin on the subscriber;
- non-overlapping partitions;
- tables are either dropped & recreated or kept unchanged during
initialization (I've tried both of these options);
- automatic identity range management;
- subscriptions never expire;
- other publication options more or less at their defaults;

I did an experiment. Stop a merge agent, add some data on a subscriber,
start the merge agent, all added data appears at the publisher. Then I did
another one. Stop a merge agent, add some data on a subscriber, reinitialize
the subscription with the "upload_first" option and generate a new snapshot,
start the merge agent. Depeneding on the "pre_creation_command" publication
option, which in my case was either "drop" or "none", added data is lost or
retained at the subscriber but doesn't appear at the publisher.

Thanks for taking a close look at this.

-- Oskar