3rd Ed SRD wrote:Spell Slots: The various character class tables show how many spells of each level a character can cast per day. These openings for daily spells are called spell slots. A spellcaster always has the option to fill a higher-level spell slot with a lower-level spell. A spellcaster who lacks a high enough ability score to cast spells that would otherwise be his or her due still gets the slots but must fill them with spells of lower level.
Could we please allow that here? I don't think it would drastically overpower any casters in particular, and would allow for perhaps more flexibility in the way people build up their mem lists...