shower elbow

I'm in the process of installing a Grohe Precision thermostatic concealed shower system with two outlets: one feeding a fixed shower head and the other feeding a hand shower hose. Both outlets connect to female threaded wall elbows that are concealed within a stud wall. I'm trying to work out...

Hi everyone. I have my 15mm copper shower pipes coming through the wall ready to mount shower fast fix kit over the top. The problem is, the elbows are showing through the wall slightly (from where the wall coating was going to be thicker) so now the fast fix kit won't push back all the way...