Hi @Peter R Thinking through some ideas on how to bootstrap the subchain system. Say you start with two miners, they could agree to communicate weak blocs between then, forming a subchain, both would benefit. The benefit to both would be maximized in a situation where they have have bad connection between them, say one inside China and its firewall, and one outside.The miner producing a weak block has an incentive share it, as it will reduce his orphaning risk if the other miner downloads and verifies it. The second miner has an incentive to download the first weak block, since the fractional difficulty proves that the first miner is trying to solve that block, and he will have it quickly to start mining on top of it of he downloads and verifies it. He also has an incentive to do his mining on top of it, as then he can share his weak blocks, and full blocks, with lower orphaning risk as well.Say the two miners each have about 5% of the total hash power on the network. If they share weak blocks at 1% difficulty, then they will on average produce about 5 blocks each, for a 10 block subchain, for every full block found on the network. About 10% of the time, one of these miners will find the full block. So if the subchain reduces the mutual orphaning risk between these two miners by 90%, for example , then the total reduction in their overall orphaning risk would be about 10% of 90%, or 9%.Once two miners are mutually benefiting from subchains, others would have an incentive to join, so the network could expand from there. I think it would also make sense for many small miners to communicate using subchains even if big miners do not participate. They could build subchains with very low fractional difficulty to reduce their mutual orphaning, thus helping them compete against big, well connected miners.