Merge coplanar triangles contained in to one quad mesh face

HI ,

I am approaching use and editing of meshes for the first time while making practice with the new SUB D toolbar available o RH7 WIP.

I am facing a basic problem but i am not able to solve it : I have a spltted mesh where several planar faces are seen by rhino as single mesh faces but as matter of fact they are formed by 3 trangular faces.
this happened after the mesh split operation and the faces affected by the problem are those laying along splitting line…
I am not able to select these planar faces in one click but i have to select all 3 triangles one at the time.

QUESTION : how can i get rid of these inner edges and have each of previously splitted faces as a single planar quad face without rebuilding each single quad face affected by this “problem” one at the time? Is there a way to fix this problem on all planar faces all at once ?