  We define the notion of C^{(2)}_{N+1} Ruijsenaars-Schneider models and
construct their Lax formulation. They are obtained by a particular folding of
the A_{2N+1} systems. Their commuting Hamiltonians are linear combinations of
Koornwinder-van Diejen ``external fields'' Ruijsenaars-Schneider models, for
specific values of the exponential one-body couplings but with the most general
2 double-poles structure as opposed to the formerly studied BC_N case.
Extensions to the elliptic potentials are briefly discussed.
