Manipulate updates due to variable changes outside manipulate: can this be stopped?

I have created a large notebook where i have two or more manipulates whose execution is supposed to wait till I click an update button. The button operates a dummy update variable which is tracked in the various manipulates as shown in the hypothetical situation below

Manipulate[update; a, {a,0,1}, TrackedSymbols :> {a, update}]
Manipulate[update; b, {b,0,1}, TrackedSymbols :> {b, update}]
update = 0; Button["update", update = 1 - update]

However, my functions in my manipulates have use a variable from outside the manipulate called "Pii2, tF2, and h2 ". These and other variables are controls inside an independent grid as shown in the second code snippet below. When I change Pii2, tF2, or h2 in the grids, both my manipulate functions described above update.

My questions: how do I keep the manipulates from updating when Pii2, tF2, or h2 are changed. I only want the manipulates to update to just the tracked variables. Any suggestions would be helpful.

Grid[{
  {Dynamic[
    InputField[   
     Dynamic[ Pii2, Initialization -> (Pii2 = SerializedData[[1]])], 
     Number, FieldHint -> "Initial Pressure", FieldSize -> Tiny]]},
  {Dynamic[
    InputField[   
     Dynamic[tF2, Initialization -> (tF2 = SerializedData[[4]])], 
     Number, FieldHint -> "Formation Temperature", 
     FieldSize -> Tiny]]},
  {Dynamic[
    InputField[   
     Dynamic[h2, Initialization -> (  h2 = SerializedData[[7]]  )], 
     Number, FieldHint -> "Net Pay", FieldSize -> Tiny]]}
  }, Alignment -> {Right, Center}]