What you have there on the Brassia is definitely a new growth emerging. You asked in the other thread if you should trim up the other part it is emerging from to give it the idea to put energy into the new growth, a short answer, DON'T TRIM!!! The new growth will get energy from the old growth while it develops it's own roots and then will begin feeding itself from it's newly devloped roots. Usually with my Brassia, I can see the new roots developing and just enjoy the show.
When it is fully grown (the new growth) you can consider splitting the plant (always leave 3 or 4 growths or more per divison). However, I personally keep mine intact unless someone is poking me for a division (like my mom or orchid lover friends).
Also, your Brassia may send out numerous growths like that in one growing season so don't be alarmed if you see more. THat is good news, probably means more flowers next season. Currently, I lost count of how many growths mine had this year, but now has 5 flower spikes on it, which is a new record for it! Most ever has been 3.... Good luck!