My Active Directory replication settings don't look right

I have recently added a new site to my Active Directory domain (single forest, single domain). I have mapped subnets to the sites, and added one DC to the new site with our remaining 4 on the original site.

As part of the configuration of the new site I looked at NTDS Settings to ensure replication was configured correctly, and things look... odd.

I've compiled a list of which servers have replication configured from other servers. I've obscured the names for security reasons but, for background:

• SERVER-A is our FSMO role holder for all roles.
• SERVER-B is a virtual instance of a DC.

Both SERVER-A and SERVER-B are Windows Server 2012 Standard.

• SERVER-C is our previous FSMO role holder which has been relegated to the role of a standard DC, no FSMO roles are held by it. This DC runs Windows Server 2003.
• SERVER-D has never hosted any FSMO roles. It runs Windows Server 2008.

SERVER-A through SERVER-D all live in the same AD Site, called BHO.

• SERVER-E holds no FSMO roles but is the sole DC in a new site, called ECO. It runs Windows Server 2012 Standard.

Ultimately, SERVER-C and SERVER-D will be demoted, removed from the domain, and have their hard disks formatted. However, I am nervous to do this because it appears replication relies quite heavily on these servers at present, particularly SERVER-C!

The list below shows each server, and the "source" servers associated with it (i.e. the servers are listed, followed by the servers which appear under the NTDS Settings page in ADS+S.

SERVER-C -> SERVER-A
SERVER-C -> SERVER-B
SERVER-C -> SERVER-E
SERVER-D -> SERVER-A
SERVER-D -> SERVER-B
SERVER-A -> SERVER-C
SERVER-A -> SERVER-D
SERVER-B -> SERVER-C
SERVER-B -> SERVER-D
SERVER-E -> SERVER-A

I am unsure what this means. If I click SERVER-C, go into it's NTDS Settings, and see Servers A, B and E listed, does this mean changes made on servers A, B and E will be replicated to C, or that changes on C are pushed to A, B and E?

My understanding is that C will receive changes from A, B and E which seems strange given that C is our "PDC" (for want of a better description). What I want is for C to push changes to A, B, D and E. And for each of A, B, D, and E to push their changes to C. Even more ideally, C and D would both be master copies, would replicate changes between themselves, but all other servers (A, B, E) would replicate their changes to one of C and D, before the change is then pushed out to the remaining servers.

I hope this explanation makes sense. Please could someone clarify whether I'm barking up the wrong tree and if so, whether it is safe to add the correct NTDS replication settings before removing the "incorrect" ones?