how to merge/mux 2 mpegts programs

[przemo1983]

I am receiving 2 multicast streams each with 1 service (MPTS TS).
I would like to merge those 2 streams info 1 MPTS stream with 2 services. Is it possible?
I am trying following command but with no luck so far:
vlc -Idummy udp://@233.0.0.1:4000 --program=1 udp://@233.0.0.1:4001 --program=2 --sout "#gather:std{access=udp,mux=ts,dst=239.4.4.4:4444}" --sout-all

[Rémi Denis-Courmont]

If the two programs are in synch, notably if they originally come from the same mux, then you can do it with secondary sources. Otherwise, no.