  We analyze the appearance of the trilinear squark-Higgs couplings $x_q$ in
Green functions in the Higgs sector of the MSSM and in threshold corrections to
the SM. The results are constraints on maximal powers of $x_q$ in QCD-related
loop corrections. In practice these often imply all-order resummations of
leading or subleading $x_q$ contributions in SM-parametrized expressions. We
present a variety of all-order resummation relations for $\Delta \lambda$ which
include such $x_q$-enhanced terms and different orders in Yukawa and gauge
couplings. We contrast which terms cannot be resummed.
