  Quantum lattice solitons in a system of two ultracold bosons near Feshbach
resonance are investigated. It is shown that their binding energy, effective
mass, and spatial width, can be manipulated varying the detuning from the
Feshbach resonance. In the case of attractive atomic interactions, the molecule
creation stabilizes the solitons. In the case of repulsive interactions, the
molecule creation leads to the possibility of existence of bright solitons in
some interval of detunings. Due to quantum fluctuations the soliton width is a
random quantity. Its standard deviation is larger than the mean value for such
a small number of particles.
