There are few strategies I've tried. They don't always work but sometimes situations will surprise me and come together.

A turn that often works is to simply ask people to work with you. A simple 'Please, work with me on this' often works wonders. It isn't a long term solution, people will eventually want to negotiate an understanding, but it might gain cooperation in the heat of a disaster situation.

This goes along with the general principle that asking goes a long way. A lot of people will help, some will make huge contributions, but they need/like to be asked. Very old school to suggest politeness and asking directly advances your cause but it is, in my experience, always a good start.

It also pays not to assume you know who the useful, versus the not useful people might be. IMO the point is to make the best of the situation where you don't have a lot of control over the raw material you are given to work with. For example don't write off the lawyers. A popular assumption is that SHTF and laws won't count. History tells a different story. Throughout history disasters may disrupt the legal system but the system always reasserts itself. You might want some legal advice during a disaster because it is pretty much a sure thing that you will be facing judgment when it all stops spinning. Helping, or failing to help, and certainly any use of force, are opening for legal issues later. A little legal advice might be good.

The other point is that people are not one dimensional. One of the finest cabinetmakers, specialized in using all hand tools and 16th century techniques, is a lawyer. It also has to be noted that just because someone is trained as a lawyer they can't tote a pack, swing an axe, herd kids, hold an injured person's hand. With electricity off and fuel in short supply a lot of things are going to have to be done by hand.

In times of uncertainty, and there are few things that sow uncertainty better than a disaster, people need to be needed. Everyone wants to feel useful and useful part of a team. A person may be borderline hysterical but if you find them a job a lot of them will settle down. Simple repetitive jobs can be calming.

Don't overlook the many paperwork jobs that need to be done. Every group disaster kit can do with a large supply of 3by5 cards and pencils. Every person has a card made out for them. Everything goes onto the card. Name, age, home address, etcetera gets noted. Then you can add special needs, injuries, skills and contact information. Nobody likes paperwork but, for better or worse, paperwork is the currency of administration and administration is the core of group management.

You can't manage a group if you don't know how many people there are. You need to know details about how many men, women, children there are. You need to know about how many people need medications. How many have special food requirements?

lawyers, administrators, secretaries, clerks, and middle management are often the best at this necessary paperwork. Use them. Orphaned children are often better off if you assign an adult to be their temporary and provisional guardian. Isolated people who are infirm and/or otherwise unable to fend for themselves may also benefit from assigning a guardian. They still need supervision but it is surprising how making such linkages can help both the guardian and their charge. Pressed into service difficult people may surprise you and shine.