If you do not wish to add on that extra row then instead of selecting the "bridge" here, in stead of selecting both inside faces just choose one and then right click and choose "put on" and then it will change screen face colors and you then select the other inside face and move your cursor off the object and right click... should have snapped things together like eh.... without the extra row in case you still needed a middle edge.... though, it should be noted as well that this method will also leave both sides as seperate objects... if this was you final smooth then great, but if you still intend to subdivide then you will get a resulting orb of tris in those two insides... if you can live with doing yet another loop cut, select, disslove, Put On then go for it 
Me, I will stick with the bridge... if I have to I can always select each edge of the bridge add on, and do a loop select, hit face, hit the minus- key so as just the new bridge area is selected, then extrude in this case x to put one more row in place... move around so as to gain even spacing and voils... still have that point center edge.
anyhoo...
It should be noted here that for all intensive purposes, the majority of details should be included in any model as soon as possible as in apposed to later on after smoothing/dividing... we have taken this example out to a finer mesh so soon onlt to demonstrate the tasks described...
take the boxy version here... the rear thrusters are boxed in at this mesh res, so would be the cockpit form, landing gear or what ever else you can think of making allowances to chunk out the basic form slightly larger in portion than would think as things scale down upon smoothing... also, remember... it is much harder to be tweaking hundreds of poly's as it is to be tweaking tens... so make those shapes boxy, add as much as possible, only then, divide out one smooth, add some more... on and on it goes eh...
happy creat'n all...
Me, I will stick with the bridge... if I have to I can always select each edge of the bridge add on, and do a loop select, hit face, hit the minus- key so as just the new bridge area is selected, then extrude in this case x to put one more row in place... move around so as to gain even spacing and voils... still have that point center edge.
anyhoo...
It should be noted here that for all intensive purposes, the majority of details should be included in any model as soon as possible as in apposed to later on after smoothing/dividing... we have taken this example out to a finer mesh so soon onlt to demonstrate the tasks described...
take the boxy version here... the rear thrusters are boxed in at this mesh res, so would be the cockpit form, landing gear or what ever else you can think of making allowances to chunk out the basic form slightly larger in portion than would think as things scale down upon smoothing... also, remember... it is much harder to be tweaking hundreds of poly's as it is to be tweaking tens... so make those shapes boxy, add as much as possible, only then, divide out one smooth, add some more... on and on it goes eh...
happy creat'n all...
