Just to be on the level...there is no 'easy' way of doing this.
First of all I am going to assume that you are picking one of the existing domains to be the final one; both domains currently have a two-way trust in place; and you want to maintainexisting accounts/groups.
Your first move should be to set up a BDC for the chosen domain in the alternate location. Make sure any replication and services are working properly. By preparing the BDC first the rest of the move will be smoother. Ifthis server is to also support WINS/DHCP make sure to set up the WINS replication with the ones sitting on the chosen domain and disable the old DHCP service the same time you activate the new one.
Your next move should be the users. You will need to mirror the existing accounts and groups from one domain on the other domain. Then make sure the newly created accounts/groups have the same access to resources as the old accounts/groups. Start having the users log into the new accounts.
Nextmove any non-PC network resources (e.g. networked printers) to the primary domain and rehome users to those resources.
If you have NT workstations/member servers (not DCs) you will need to now remove them from the old domain and add them to the chosen domain.
PDC/BDCs on the old domain will be the difficult part. Some say that you can remove a BDC from one domain and add it to another but I haven't seen this done reliably. Your best bet is to back up each individual server and rebuild it adding it into the chosen domain in the process then restoring the data back to the server. You will definitly have to do this to the old PDC!
The old PDC will be the last thing to go. Make sure you drop the trust is has with the chosen domain before you bring it off-line. This will prevent errors on the chosen domain.
I have never messed with Lotus Notes myself so I can't give you any guidence there. Good luck!
