If i understand correctly, The nurses at 'his' dialysis center have been trained to do a particular job, so he needs to go there, and yes, there has to be someone else more suited to do a temporary move. I know how he probably feels about 'getting his way' because though i will fight for my 'way' on things like this, i always worry about retaliation, BUT.,,,,,,,,,,, in these situations, you only get your way because your right and we have never seen further objections to any particular situation. I would hope you could stick with your usual place for D, as without training, they may just say 'no can do' and then you have another situation
I wish you well... This is hard