  Massless flows from the coset model su(2)_k+1 \otimes su(2)_k /su(2)_2k+1 to
the minimal model M_k+2 are studied from the viewpoint of form factors. These
flows include in particular the flow from the Tricritical Ising model to the
Ising model. By analogy with the magnetization operator in the flow TIM -> IM,
we construct all form factors of an operator that flows to \Phi_1,2 in the IR.
We make a numerical estimation of the difference of conformal weights between
the UV and the IR thanks to the \Delta-sum rule; the results are consistent
with the conformal weight of the operator \Phi_2,2 in the UV. By analogy with
the energy operator in the flow TIM -> IM, we construct all form factors of an
operator that flows to \Phi_2,1. We propose to identify the operator in the UV
with \sigma_1\Phi_1,2.
