Q: iTunes library and Apple Music

I'm having problems with my iTunes and Apple Music libraries

I sync my music from my iTunes onto my iPhone then switch on my apple music account and merge both my libraries but when this happens it removes a lot of the music that was synced from my iTunes onto my phone (mostly music that is not available on Apple Music live albums etc).

Is there anyway of being able to have all of my synced music from iTunes and my apple Music library my iPhone  at the same time?

Any help would be much appreciated