Hi @v-yutliu-msft
I gave in a good go but just cant get this to work
I was able to have both a collection and non collection gallery pulling up records that are not in my junction gallery.
The patch direct gave me this.
Patch(Program_GroupHostJunction,Defaults(Program_GroupHostJunction),{StudentID:StudentIDTT,STUDENTTitle: StudentTitleTT,GROUPTitle: GroupTT,ID:StudentGalleryNotInJunction.Selected.ID,Title:StudentGalleryNotInJunction.Selected.Title,GroupTitle:StudentGalleryNotInJunction.Selected.GroupTitle})

Says GroupTitle does not match expected number, found text type. But that is a text type field. Actually it is a lookup on the students list but its not number/ I tried putting "Selected.'GroupTitle'" but not change.
The other Patch from Collection formula I've tried is
ForAll(RenameColumns(Filter(ColStudentNotinList, Ischosen), "ID", "EID"), Patch(Program_GroupHostJunction, LookUp(Program_GroupHostJunction, ID=EID), Defaults(Program_GroupHostJunction), {STUDENTTitle: StudentTitlelabel},{StudentID: StudentID7, GROUPTitle:Label31 }));
ClearCollect(ColStudentNotinList, AddColumns(Program_GroupHostJunction, "Ischosen", false))
Am I close?