Objective: I am trying to make a a graph consisting of two graphs 1) a base surface plot 2) a rectangular region that represents the Quadratic Approximation at a specific point(x0,y0)

Here is the Code:

Manipulate[
 Show[basePlot, 
  Plot3D[coEfficientOne + (coEfficientTwo*(y - 
        y0)) + (coEfficientThree*(x - x0)*(y - 
        y0)) + (coEfficientFour*(x - x0)^2) + (coEfficientFive*(y - 
         y0)^2) + (coEfficientSix*(x - x0)), {x, x0 - \[Pi]/4, 
    x0 + \[Pi]/4}, {y, y0 - \[Pi]/4, y0 + \[Pi]/4}, PlotStyle -> Blue,
    PlotRange -> All]], {x0, -2 Pi, 2 Pi}, {y0, -2 Pi, 2 Pi}]

NOTES: All the Coefficient variables are the coefficient terms of the Quadratic approximation of a function of two variables. The coefficients are made up of elements of x0 and y0 only

Please Help Thanks!