Search for targets within selected cell line group

Hi there,
I have just started using the tool. I am interested in looking spefically at gastro/ oesophageal lines. I managed to create a cell line group and select all the lines, which I can then filter for when looking at it under perturbation effects.
However I would like to select only this group in the target discovery page - specifically, I am trying to find targets for gastro/ oesophageal cancers, and as far as I can tell, this is the best (only?) way to do this.
Thanks for your help