The Siyum HaRambam this year falls in the middle of the 9 days and we are in camp. Is there a היתר to play music and serve meat at the Siyum?
There is no Heter to play music. Eating meat is permissible; it’s the same as one who made a Siyum Mesechta)
and if not, can we push off the Siyum?
If it will bring more Kavod Hatorah it should be pushed off.
If we could, should we still learn the last Halacha and first Halacha of Mishneh Torah and then Chazzer them, or skip them and make a real Siyum?
Finish on the proper day and then you can explain with more detail during the Seudas Siyum.
עיין סה”ש תנש”א ע’ 89 ושם הע’ 10.