Josh,
there are 2 ways to do this without using Multiply. Just give the stroke a color.
In both cases you need to break the link to the symbols.
In the first example the leaves group was made into a Live Paint Group: Object > Live Paint > Make and immediately expanded: Object > Live Paint > Expand.
This creates 2 groups in the Layers panel, one with the white fills and one with the strokes. just turn off, or delete, the white fill.
In the second example the symbols were expanded and the white fills were set to 0% opacity.
The group was given an Opacity attribute of Knockout Group in the Appearance panel.
The advantage is that the individulal leaves can still be repositioned. The problem is that many (non Adobe) PDF viewers ignore the knockout group.
In the screendump you will see the outline view below to show the difference.
![Leaves.png](/legacyfs/online/1812247_Leaves.png)