Using Vicon as external position estimator with snapdragon

Hello ,
I’am trying to set up Vicon as external position estimator for Snapdragon flight with PX4 as Firmware.

First: following the tutorial here https://dev.px4.io/external-position.html , I start by adding local_position _estimator start in the px4.config and disable efk2 start. The data I send via the /mavros/mocap/tf (even tested it with /mavros/mocap/pose) aren’t used as local position. The messages from /mavros/local_position/pose are completely differents from my vicon data.

Second: I tried to follow this tutorial https://dev.px4.io/advanced-fake-gps.html but I am stucked at modifying mocap_fake_gps.cpp since I don’t have this plugin in my mavros_extra (ROS INDIGO).

So my big question is how can I use external position with Snapdragon ? the PX4 firmware upload in the snapdragon is this recent branch from ATLFlight : GitHub - ATLFlight/Firmware at fix/parameters_xml_synchronization.

Thanks in advance for your answer