In Pen and Paper (and yes, I know this isn't the same beast anymore), using metamagics involves memorizing a spell at X levels higher than the original.
My suggestion is to bring this functionality to DDO by giving casters the equivalent of our already-existing weapon-sets. On the Spells tab of your character sheet, you could drag (for example) Web to the first spell-set slot. Then drag Heighten to it. This way, you could cast heightened webs without them being extended or quickened if you've got the global toggle on.
p.s. There will be a post-nuptials reception at the Golden Wing Inn in House Phiarlan following the event. Sorry, but due to Elven restrictions, there will not be an open bar.