It's much easier to find replacement managers to take over orphans rather than just nuking the teams & adding those players to free agency. that's a last ditch move. Try advertising for ppl to take the orphans first. If that doesn't work, what I usually do is just dump all the players into the main draft - the main rookie/vet draft - the players will get dispersed fairly that way & it will spice up your rookie draft. just my 2 cents

I've been in a few dispersal drafts in my time and they have always been done using spreadsheets (Google sheets is perfect) and a decent chat program like Discord or Groupme. Not aware of any platform that has a better solution, and Flea certainly does not. As MonteM says, you need a commissioner with a brain who is willing to put work into the spreadsheet and the chat-based draft. Good luck.

First of all this is not Mildly Above-Average commissioning and neither is losing 3 teams to have an odd number, so you ought to change your League's name.

Second you can't officially have a dispersal draft, but you could have a draft for only rookies and then a supplemental draft for veterans and rookies. That's probably going to mess up your draft picks though, so you'd be better off having the dispersal draft on the League's Message Board and then Import team's picks by using Edit Rosters. It is a bit more work as the Commish but it would appear someone in your league needs to step up and be Mildly Above-Average. Good luck.