Noteflight has been immensely helpful to both myself and my students. I personally use this program quite often to rearrange parts as needed, or simply send my students the link to refer to the mp3 of their part.

How I Use It

I use this personally to write parts, rearrange parts, clean up hard to read parts, and more for my band students.
I also use this to upload mp3's of my students' parts to their remind group and office 365 group to refer to while practicing at home. This has been helpful for students who need to hear and see the music as it goes to really understand how their part works, and to hear their individual part outside of the general ensemble sound.