Can i “group” photos? Is this a PRO feature?

Hi,

i need to “group” my photos! Currently the “rel” tags of my images are “prettyPhoto[pp_gal]”, so all of my images, from all of my galleries are shown. I want to change it to something like “prettyPhoto[pp_gal1]”,”prettyPhoto[pp_gal2]”, etc

Is there a way to do this? Is this a pro feature?

Thanks!