Selecting objects on magic sheet

When editing my magic sheet, I would like to select a group of instruments without selecting the underlying objects.  Specifically, I have the pipes the instruments are on shown as lines grouped together.  Whenever I select any group of instruments where one of these pipes (in the pipe group) is wholly within the selection box, the entire pipe group gets selected.  I tried shift-click to deselect it, but that only adds to a selection, not deletes from it.  Is there any way to lock a group so it can't be selected?  How can I select these instruments other than by clicking them one-by-one?  Is there a way to not select the entire group, just because an object within that group falls within the selection range? It's common to use layers for something like this, but I don't see anything like that.

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