Right Frontier Constraint (RFC) is a principle widely used across discourse theories because it manages to explain a wide variety of discourse phenomena. However, interleaved structures, described for example in (Asher, 1993), seem to constitute a problem for the standard version of this principle. These constructions have been described as allowing discourse attachment to closed off constituents contrarily to RFC predictions. We aim at proposing a treatment of two-step enumerative structures (Porhiel, 2007) based on some recent contributions on enumerative structures (Bras et al., 2008). We take this specific structure as an entry point for more general interleaved constructions that constitute a crucial challenge for discourse structure theories.