Let G be an exponential solvable Lie group and H a connected Lie subgroup of G. Given any discontinuous subgroup for the homogeneous space M = G/H and any deformation of , the deformed discrete subgroup may utterly destroy its proper discontinuous action on M as H is not compact (except the case when it is trivial). To understand this specific issue, we provide an explicit description of the parameter and the deformation spaces of any abelian discrete acting properly discontinuously and fixed point freely on G/H for an arbitrary H of a threadlike nilpotent Lie group G. The topological features of deformations, such as the local rigidity and the stability are also discussed. Whenever the Clifford-Klein form \G/H in question is assumed to be compact, these spaces are cutely determined and unlike the case of Heisenberg groups, the deformation space fails in general to be a Hausdorff space. We show further that this space admits a smooth manifold as its open dense subset.