How do I switch my Texas medicaid provider from Texas STAR Program to Community Health Choice?

I just found out the the star program only pays for 1 ultrasound for my entire pregnancy and I can't deal with that but I don't know how to switch to CHC which offers at least three.How do I switch my Texas medicaid provider from Texas STAR Program to Community Health Choice?call star and tell them you want to switch over I'm sure they will walk you through it