For your PGIE + multiple SGIEs case, multiple branches are not necessary. The parallel pipeline may not be faster than the normal pipeline like /opt/nvidia/deepstream/deepstream/sources/apps/sample_apps/deepstream-test2
You can try this parallel pipeline under the /opt/nvidia/deepstream/deepstream/sources/apps/sample_apps/deepstream-test2 directory.
gst-launch-1.0 nvstreammux batch-size=2 width=1920 height=1080 name=mux ! nvinfer config-file-path=./dstest2_pgie_config.txt batch-size=2 ! nvtracker ll-config-file=/opt/nvidia/deepstream/deepstream/samples/configs/deepstream-app/config_tracker_NvDCF_perf.yml ll-lib-file=/opt/nvidia/deepstream/deepstream/lib/libnvds_nvmultiobjecttracker.so display-tracking-id=0 ! tee name=t t.src_0 ! nvvideoconvert ! 'video/x-raw(memory:NVMM),width=1920,height=1088' ! nvinfer config-file-path=./dstest2_sgie2_config.txt ! nvmultistreamtiler width=1920 height=2160 rows=2 columns=1 ! queue ! nvdsosd display-text=1 display-bbox=1 ! nveglglessink uridecodebin uri=file:///opt/nvidia/deepstream/deepstream/samples/streams/sample_1080p_h264.mp4 ! mux.sink_0 uridecodebin uri=file:///opt/nvidia/deepstream/deepstream/samples/streams/sample_1080p_h265.mp4 ! mux.sink_1 t.src_2 ! queue ! nvvideoconvert ! 'video/x-raw(memory:NVMM),width=1920,height=1088' ! nvinfer config-file-path=./dstest2_sgie1_config.txt ! nvmultistreamtiler rows=1 columns=2 width=3840 height=1080 ! nvdsosd ! nveglglessink