Difficulty with SF2 files containing multiple sounds; only one sound will play

Here's my difficulty. I know exactly how to install SF2 soundfonts on my computer, I have used them in several compositions, but there's one limitation I havent been able to overcome.

Some soundfonts, as you probably know, contain multiple sounds. My problem is that when I have a multi-sound SF2 selected, I can only get GarageBand to play one sound -- presumably the first one in the pack. There are no options in the DLS Music Player window for selecting other sounds within the soundfont; only the soundfont itself is listed. I have a couple of soundfont packs where the different sounds are all split into individual SF2s within a folder, and that displays as a submenu properly... but I can't get these others to work properly. Any ideas?