I'm quite a noob with tvheadend; but as you didn't get any other responses: I've been playing around and testing different setups with tvh on Raspberry Pi2. I want to provide the channels via Sat>IP (port 554). If I have a TVH Server correctly set up, providong its channels via Sat>IP I automatically see them in the sources list of another TVH. So at least using SatIP it should work?
--did I understand that correctly: you want to daisy-chain them, so: Source -> TVHeadend1 -> TVHeadend2 ?)