The paper is sacrificed to discussing the property of some special subfamily F of the family of all permutations of ℕ, especially in the context of the fundamental properties of families C and D of the, so called, convergent and divergent permutations, in other words, permutations preserving or not preserving the convergence of the rearranged real series, respectively. Family F is the subgroup of the group G generated by C. In the paper we will prove, among others, that F ⊂ C