Ah yes, this can be done already, but to be prompted for which smallpack batch should be used, you need to have “Auto assign smallpack” disabled in your delivery settings. I realise this seems a bit silly, so I’ve already raised a feature request for Allow choosing of specific batches of smallpack stock to move between locations when auto-assign is enabled. Can you give this a vote?
In the meantime, assuming you do want to keep “Auto assign smallpack” enabled, you can briefly disable this each time that you need to move stock, but of course, we’ll look to split this setting up to save this hassle.
Cheers!