OK in Logic speak, a Multi Instrument is an Environment object managing 16 external MIDI channels, so disregard what I wrote and thanks for the explanation. You're talking about Multi Out Aux channel strips (I guess?) which can of course not be negative-delayed individually as they only transport Audio signals.
What if you set a "large enough" negative delay on the Instrument track and insert a Sample Delay plug-in in each multi-out aux, set its "Unit" to "ms" and add a positive delay to adjust the individual aux delay (which would then be the (negative) instrument delay plus the (positive) aux delay)?