integrate 2 domains

Hi,

Could you please help advise on the options of using ADMT V3.2 to integrate 2 domains(domain1.int, and domain2.int)?

Current setups:

Currently, there are 2 existing domains(domain1 and domain2) set up as follows:

1. Both domain DCs running a mixture of Windows server 2008 r2 Ent and Win2003 server.
2. DCs of domains are physicall located inside a same room,
3. but domain1 and domain2 are “separated “–  each keep its own set of AD DS database, DNS, DHCP. although the server machines are located in a same room, but are linked to different cisco switches in a way to prevent any connection between the 2 LANs/Domains.
4.  in BOTH of AD, each staff is given/using an account in both domains -- EACH of staff  has a user accounts in both domains(e.g MikeLee\domain1, Midelee\domain2, the passwords are maintained by respective AD, thus the same user has 2 sets of account/passward).
5. there're 2 separate LANs, each PC is only possible to link to one particular domain(and the DCs of that respective domain), a user can only log in to a particular domain(either domain1 or domain2) using the account/machine of that domain(id-at-thatdomain,  as well as the machine-joinedto-thatDomain).
6. Among 200 staff, 30 of them are “active” in domain1(their PC account & homedrive in domain1, and most of time they log in to domain1); the rest of 170 staff are “active” in domain2(their PC joined to domain2, most of time log in to domain2, home drive in domain2).

New requirement to merge or integrate (domain1 and domain2)

Now, we need to maintain only 1 single domain instead of 2, as most of users in domain2, so it seems reasonable to keep domain2 and migrate those from the domain1 to domain2. 

Could you please advise what are the best solutions to the requirement?

Thanks a lot for your help and support!

Warm regards,

waterlily901