  Thermal and magnetic effects in a system consisting of thin layers of coupled
Ising spins with $S=1/2$ and $S=1$ are considered. The specific heat and the
correlation length display maxima at two different temperatures. It is
discussed in what sense these maxima can be interpreted as a finite-size
rounding of a thermodynamic singularity associated with a phase transition. The
connection with ordinary, extraordinary and special surface phase transitions
is made. In $2D$, the surface critical exponents are calculated from conformal
invariance. The bulk and surface finite-size scaling of the order parameter
profiles at the transition points is discussed. In $2D$, an exact scaling
function for the profiles is suggested through conformal invariance arguments
for the (extra)ordinary transition.
