grigri for multipitch?

It is hard to make dynamic belaying on a multi pitch and a grigri directly in the belay will create the most static falls which is not recommended. If your friend falls after just few meters climbing, there is a risk that he/she can get injured. If you are only comfortable with a grigri put the carabiner in the belay loop and try to stand with sligthly bended knees when belaying.

would it be better if you use a very good rope that reduces the static power? reason is why im asking and need some opinions: is my girlfriend got burned hands  when i took quite a long fall and she was belaying via the anchor with the HMS knot. grigri on multipitch directly in the belt loop isnt such a good idea either i think as she might hit the wall when shes belaying only with her feet pressed against the wall on a bad multipitch stand.

One alternative is to buy some belay gloves because, if you had been using the grigri carabiner directly in the belay station, maybe you had been injured. Every dynamic rope is more or less similar dynamic. A new rope is more dynamic compared to an old one.