How to find and replace missing vias in layout using Skill function

Hi,

I have designed some analog/RF blocks in a 5 layer SiGe technology process. Now, i want to re-use the same blocks in a 7 layer SiGe technology process. The two processes are exactly same apart from the 2 additional metal layers which has been added to get 7 layer process. When i open the layout of any RF block(designed in 5 layer process) in 7 layer process, everything is fine apart from the flashing signs which i get where ever interconnection between different metal layers are performed using vias since vias for 2 additional metal layers are missing. I will try to explain it in a better way below:

Process A (5 Layers)          Process B (7 Layers)

M1                                          M1
M2                                          M2
M3                                          M3
M4                                          M4
M5                                          Mx
                                                My
                                               M5

Now, i get missing vias error wherever, M4 to M5 interconnection is present since in 7 layer process, two additional vias are needed to go from M4 to M5 compared to 5 layer process.

Since the designed block is quite complex and hierarchical, it is quite tough and time consuming to locate the missing vias positions and adding missing vias manually at all such positions. Can a program be written in skill to search for the missing vias position and then adding the 2 missing vias in whole layout of the complete block automatically ? 

If yes, can you direct me towards any documents/examples regarding what is the most efficient way to achieve above described goal ? I would like to write a skill function, which on execution can find and replace all stacked vias(5 Layers process) with newly 7 layer stacked vias. Any help in this regard would be great.

/Sohaib