a simplification problem



I have the following terms

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display2d : false;

t1:(J(r,a+1,b,s+1,t)*(-s+a+1)-J(r,a,b+1,s+1,t)*(a-s))*(t+r+1)
 +(s+r+1)*(J(r,a,b+1,s,t+1)*(-t+b+1)-J(r,a+1,b,s,t+1)*(b-t));

t2:(s+r+2)*((-t+b+2)*((J(r,a+1,b+1,s+1,t+1)*(-s+a+1)
                  -J(r,a,b+2,s+1,t+1)*(a-s))
                  *(t+r+2)
                  +(s+r+1)*(J(r,a,b+2,s,t+2)*(-t+b+1)
                           -J(r,a+1,b+1,s,t+2)*(b-t)))
        -(b-t)*((J(r,a+2,b,s+1,t+1)*(-s+a+2)
               -J(r,a+1,b+1,s+1,t+1)*(-s+a+1))
               *(t+r+2)
               +(s+r+1)*(J(r,a+1,b+1,s,t+2)*(b-t)
                        -J(r,a+2,b,s,t+2)*(-t+b-1))))
 +(t+r+2)*((-s+a+2)*((J(r,a+2,b,s+2,t)*(-s+a+1)
                    -J(r,a+1,b+1,s+2,t)*(a-s))
                    *(t+r+1)
                    +(s+r+2)*(J(r,a+1,b+1,s+1,t+1)*(-t+b+1)
                             -J(r,a+2,b,s+1,t+1)*(b-t)))
          -(a-s)*((J(r,a+1,b+1,s+2,t)*(a-s)-J(r,a,b+2,s+2,t)*(-s+a-1))
                 *(t+r+1)
                 +(s+r+2)*(J(r,a,b+2,s+1,t+1)*(-t+b+2)
                          -J(r,a+1,b+1,s+1,t+1)*(-t+b+1))));
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t1 and t2 were generated with a recursion rule.
t1 and t2 are linear combinations of the J-Terms and r,a,b,s,t are parameters.

Is it possible to combine the J-Terms and apply a function,
e.g. factor(), to their coefficients?

Andre