[Mosh]

If they are template edits then you will have to apply them all manually to your new style, as changes are usually applied to the style currently assigned as the forum default style.

When you had other styles as child styles to the original style, hacks applied to that style would be inherited by the child styles apart from if there were any alterations to the child styles templates directly.

There is no way currently for all styles to be updated simultaneously, unless some creates a hack to do it.