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As in you want to level up a spell, add more spells to a wand, or rank up a wand?

Leveled up spells are unique spells on their own. So you simply add them to a wand, they will replace any lower-levelled versions already on the wand.

They have special "key names", so like "/wand add apparate|2" will add apparate level 2. The character there is a pipe, normally shift+backspace.