Abstract The recent progress in nanotechnologies is giving birth to a novel topology of wireless networks characterized by a high local density and an intensive node instability such as in WBAN and swarm micro-robots systems. In this paper, we show that classical and dedicated ad hoc nanonetwork routing solutions are inefficient in this case and present a low reliability level and add a supplementary delay and control traffic. Majority of these solutions are based on point to point relaying mode, which is not adapted to the instability context. The multirelay to multirelay approaches allow countering the problem of nanonodes uncertainty by using the high number of inter-node connections. However, these approaches perform badly when the nanonetwork deployment presents distortions and concave sides. We propose a new routing protocol called Multirelay to Multirelay Routing Protocol (M2MRPv2), which provides a natural way to manage the residual energy levels on the nanonodes. M2MRPv2 is, to the best of our knowledge, the only approach that proposes a proactive multirelay to multirelay routing mode where the residual energy level of the nanonodes and reliability of the routing paths are taken into account. We study the performances of multirelay to multirelay protocols according to different multi-source to multi-sink communication scenarios. The obtained results show that M2MRPv2 protocol outperforms by far the Sustainable Longevity Routing (SLR) protocol (the reference protocol for Terahertz nanonetworks) in terms of transmission reliability and energy management. This outperformance is accentuated when the Terahertz nanonetwork deployment presents many concavities.