  We consider one-dimensional hierarchical coalescence processes (in short
HCPs) where two or three neighboring domains can merge. An HCP consists of an
infinite sequence of stochastic coalescence processes: each process occurs in a
different "epoch" and evolves for an infinite time, while the evolutions in
subsequent epochs are linked in such a way that the initial distribution of
epoch $n+1$ coincides with the final distribution of epoch $n$. Inside each
epoch a domain can incorporate one of its neighboring domains or both of them
if its length belongs to a certain epoch-dependent finite range. Assuming that
the distribution at the beginning of the first epoch is described by a renewal
simple point process, we prove limit theorems for the domain length and for the
position of the leftmost point (if any). Our analysis extends the results
obtained in [Ann. Probab. 40 (2012) 1377-1435] to a larger family of models,
including relevant examples from the physics literature [Europhys. Lett. 27
(1994) 175-180, Phys. Rev. E (3) 68 (2003) 031504]. It reveals the presence of
a common abstract structure behind models which are apparently very different,
thus leading to very similar limit theorems. Finally, we give here a full
characterization of the infinitesimal generator for the dynamics inside each
epoch, thus allowing us to describe the time evolution of the expected value of
regular observables in terms of an ordinary differential equation.
