Legacy Support per NBU 6.x and Master Server 7.5.x

Hi all,

I need informations about compatibiliy Legacy Support per NBU 6.x, I have Master Server 7.5.0.x,two media server 6.5.6 and  Client 6.5.6...if I would replace media server 6.5 with 7.5.0.x, could I backup this client without upgrade clients to 7.5.0.x ?

I search and write every document about this, but I don't understand it.

thanks a lot

Rick