[ericbsmith]

Select the advantage you want to collect everything under, right-click on it, and choose "Make Parent."

Then select all of the items you'd like to organize under the advantage; click select, then shift+click will allow you to select several items in a row; ctrl+click will allow you to select multiple items one-by-one. Once they're all selected, right-click on one of them and select "Make child of..."

Each trait type has a _New Parent Item which is already set as a parent container when added to the character that other traits may be made a child of. Some container equipment (such as bags, backpacks, and jugs) are also already set as parent containers. I generally suggest using the _New Parent Item as a 0-point trait because point costs can look a little wonky if you use an existing trait to organize other traits under.