This short item on the Antiference Exstat aerial systems mentions the multiple receiver case:
Specifically:
“Special receiver transformers are available to provide for multi-point reception where a number of receivers are required to operate from one aerial”.
No details were given, but it could have been as simple as equipping the receiver transformers with both inputs and outputs for the screened feeder to enable easy daisy-chaining.
Another professional system, this time from EMI and intended for use in apartment blocks, is described in this article:
EMI Aerial Distribution System WW 195602.pdf
Whilst the main topic addressed was Band III television, it may be noted that the distribution system included “all-wave radio”, presumably 150 kHz to 26 MHz or so, as well as VHF TV and FM. At the distribution boxes the signals were separated by low-pass (all-wave radio), bandpass (FM) and high-pass (VHF TV) filters. Presumably these were arranged to present an appropriate source impedance in each case, 75 ohms for FM and TV and a high impedance for all-wave radio, to match typical domestic receivers.
Cheers,