The superintegrability of four Hamiltonians Hr = λ Hr, r = a, b, c, d, where Hr are known Hamiltonians and λ is a certain function defined on the configuration space and depending of a parameter κ, is studied. The new Hamiltonians, and the associated constants of motion Jri, i = 1, 2, 3, are continous functions of the parameter κ. The first part is concerned with separability and quadratic superintegrability (the integrals of motion are quadratic in the momenta) and the second part is devoted to the existence of higher-order superintegrability. The results obtained in the second part are related with the TTW and the PW systems.