  Structural, magnetic (M) and thermal (C_m) studies on Ce_2(Ni_{1-y}Pd_y)_2Sn
alloys are presented within the 0<y<0.55 range of concentration, showing
evidences for itinerant to local electronic transformation. At variance with
RKKY type interactions between localized moments \mu_{eff}, the substitution of
Ni by isoelectronic Pd leads the antiferromagnetic transition to decrease from
T_N~3.8K to ~1.2K between y=0 and 0.48, while M(H) measured at H=5Tesla and
1.8K rises from 0.12 up to 0.75\mu_B/Ce-at. Furthermore, the C_m(T_N) jump
increases with concentration whereas |\theta_P| decreases. The magnetic entropy
S_m(T) grows moderately with temperature for y=0 due to a significant
contribution of excited levels at low energy, while at y=0.5 it shows a
incipient plateau around S_m=Rln2. All these features reflect the progressive
ground state transformation of from itinerant to a local character. Another
peculiarity of this system is the nearly constant value of C_m(T_N) that ends
in an "entropy bottleneck" as T_N decreases. Consequently, the system shows a
critical point at y_{cr}~0.48 with signs of ferromagnetic behavior above
H_{cr}~0.3T. A splitting of the C_m(T_N) maximum, tuned by field and
concentration, indicates a competition between two magnetic phases, with
respective peaks at T_N~1.2K and T_I~1.45K.
