Di/Di twins + amnio + Kell antigen

Ke
Hello!
I'm 34yo and 16.5 weeks pregnant with didi twins. I'm going for an amnio later this week because at around 8 weeks, I found out after initial blood tests were taken, that I have the kell antigen. (Got it as a result of my first pregnancy with my daughter, who had K from her dad/my husband.) Docs want to determine if either twin has K blood type, and treat accordingly from there.
I'm super nervous about the amnio and about the kell--wondering if anyone out there has advice or words of wisdom/comfort about amniocentesis with twins and/or Kelly with twins. There's not a whole lot out there on the web to give me any sort of reference.
Thanks!