Sql Server 2000 Installing Database On New Sql Server 2000

Problem description

There are two sql servers with the same database in different locations with replication running on them. Users in the two locations insert or update date on there own database through an ms access application . The data are replicated to both servers.
Someone wanted a copy of the database and they dropped replication, but users continue to modify and add data on both servers and so replication could not be back again without merging the two databases as one again and restarting replication.
My job was to merge the databases and make replication work and after allot of work all is fine.
I copy and attached the database on my pc that I set up as a server and did the job. Then I went back on both servers that had replication running before I attached the database and set the subscriber and publisher and all was fine to that point.
The database has six groups with permissions on them and many database users on each location. Both the groups and the users show on the database.
I create a new login and user and I add him to the groups to get the permissions.
Now back on a user pc I login with the new user name run the ms access application and try to add some new records, but I get errors that I cannot insert null values to two of the fields in several tables in the database.
This was not happening before and the database was recording the values in those fields namely the user name and the date that the new record was created.
After some reading I found out that I might need to set the groups and permissions on the views and tables from the beging but Im not an expert.
Any ideas?
Thanks allot
George