Installation of in-wall speakers

Not exactly sure of your room layout. Your question is a bit confusing as well….

• I am installing 2 sets of in-cieling sonos speakers in my kitchen and the adjacent dining room I wanted to put in-wall speaker/s.  My question is do I need to put a pair of in wall speakers (3rd in parallel series) or can I just put one in in-wall speaker?

Can you submit a diagram and approximate where you want the speakers?. You should also know that if you plan to only use one Amp the same music will be heard in both rooms. 

Option 1 would be my choice. However, unless you have an overly large kitchen I question why four (4) speakers. Two centrally located mid-center would seem to be adequate running north to south. South being the wall shared with the dining room.

If you are planning on running them in mono I'd go with 3.

If you were thinking stereo then the 2 ceiling ones would be good but the single would only play one stereo channel, two would be better.

Kitchen is roughly 750 sq ft plus an area not in the diagram 14 x 8 that is cathedral ceiling.  just what remodel company recommended in kitchen “based on experience,” probably overkill

Not sure it is wise to able them to each other instead of cable connect all speakers directly to the Amp.