Learn English – Being them / being themselves

I believe that I agree with Sander that "these" is valid there, but I agree with you that it's not how I would construct the sentence. I would use "them", or in a more formal document I might use "the same".

One could take among themselves to mean that the debates were held within the various branches intramurally rather than between the branches.

Consider:

There were various delegations in the auditorium, debating among themselves which candidate to vote for.

I would take that to mean that each delegation was having its own debate, not that there was an open floor debate.

On the other hand, debating among them would mean there was an open debate, the delegations debating each other.