If you're going to house your new acquisitions together with your now establish pair of Bolivian rams (ie: in the same tank) I suggest that you would go for either a pair of kribs (which are very hardy) or a pair of apistos. I wouldn't choose a pair of tanganyikan, if you still want to keep your current fish, as they come from different continents, with different water parameters, habitats, etc.
Also note, that by adding another pair of kribs or apistos, I would stop adding cichlids after as you would be quite on the high side of the risk, when it comes to territory.
Wish you luck, and as always keep us updated with those beautiful pics you post.
P.S. If you're interested in apistos, then the following link may be of use 
.. http://www.forum.apistogramma.com/index.php