Say you had a 3x3,
BCD
EAF
GHI
Therefore, A is potentially:
A = A(B + C + D + E + F + G + H + I) or
AB + AC + AD + AE + AF + AG + AH + AI
B = B (A + C + E) or
BA + BC + BE
Etc, etc. And those are only flanking cards...
If you decided to mirror something say... B & D, then BD, if you decide to knight I, then you can only knight with C and E, so I = I (C + E) --> IC and IE. I'm using the math here for those that enjoy math... It might help them understand what is happening. So yes, to answer your question, the combinations are valid...
The problem in using all this math is that you can over do it. It's just a subjective exercise to get your intuition to understand what the story is, you might get a clear enough message by reading less cards, and not have to resort to all the possibilities.
Hope that makes sense.