Glad,
Perhaps I can help here a little on F-35 systems operation. The following information uses open sources, by the way.
The F-35 'data fusion' (or 'sensor fusion' if you prefer) across platforms is supported by the MADL system (Multifunction Advanced Data Link), which is installed on the platform in a number of locations so as to provide full spherical coverage.
This is a steered beam system, which uses differential GPS to allow pairs of aircraft to establish a beam link. Yes, the jets are transmitting, but the system is designed for Low Probability of Intercept (LPI), like modern radar altimeters and other RF systems.
There's some information out there, understandably restricted at this stage.
Hope this helps,
Best regards
Engines