I have a long expression, only representative terms are given below. As a first step, I want to collect terms in terms of u[x,t] and its derivatives.  The second step is to make those coefficients equal to zero as separate equations.
For example, if I have the expression:


    xpr=a[x, t, u]*Derivative[1, 0][u][x, t] + 2*Derivative[0, 1][u][x, t]*
    Derivative[1, 0][u][x, t]*Derivative[0, 0, 1][b][x, t, u] + 
    2*u[x, t]*Derivative[1, 0][u][x, t]^2*Derivative[0, 0, 1][b][x, t, u] + 
     2*Derivative[1, 0][u][x, t]*Derivative[1, 1][u][x, t]*Derivative[0, 0, 1][c][x, t, u]+2*Derivative[0, 1][u][x, t]*
    Derivative[1, 0][u][x, t]*Derivative[0, 0, 1][d][x, t, u];

The first step should result in:

    stp1=a[x, t, u]*Derivative[1, 0][u][x, t] + 2*u[x, t]*Derivative[1, 0][u][x, t]^2*
    Derivative[0, 0, 1][b][x, t, u] + 2*Derivative[1, 0][u][x, t]*
     Derivative[1, 1][u][x, t]*Derivative[0, 0, 1][c][x, t, u] + 
    Derivative[0, 1][u][x, t]*Derivative[1, 0][u][x, t]*
     (2*Derivative[0, 0, 1][b][x, t, u] + 2*Derivative[0, 0, 1][d][x, t, u])

The last step will give rise to:

     eqns={a[x, t, u] == 0, 2*Derivative[0, 0, 1][b][x, t, u] == 0, 
      2*Derivative[0, 0, 1][c][x, t, u] == 0, 
      2*Derivative[0, 0, 1][b][x, t, u] + 2*Derivative[0, 0, 1][d][x, t, u] == 0},



Your help is much appreciated.