I actually just recently replied to a similar thread with some suggestions, so I'll copy and paste here:
-Depending on the province you're returning to, you might not have health insurance right away, like Ontario. Get in touch with a private insurance company like Blue Cross or whoever, get a quote for the 3 or so months you'll be waiting to get re-enrolled in the health system.
-Provide screenshots of you searching for return flights and rental/house buying. Of course the VO understands you won't be able to buy or rent property until you have PR approved, but showing that you're doing intense research in your desired area is another layer of evidence
-If you have any old work contacts, ask around about jobs in the area you want to live, see if they know of anyone hiring. Additionally, put together a resume, and start getting into contact with help wanted ads back home. Even if these jobs don't pan out, it shows them you are making serious inquiries about a job
-Get some letters from friends saying they know of your intent to return, you have discussed it with them, it shows you are serious about this. If you have any private message screenshots discussing this to attach with the letters, that would also help
-Are you planning on bringing items other than clothes back to Canada? Stuff like couches, tables, chairs, beds etc? Get in touch with a moving company and get a quote and attach that to your application.
-I've seen others do this. Write a detailed "game plan" of what you and your partner intend to do once PR is approved. Stuff like getting them a SIN, a bank account, a driver's license, jobs for the two of you, buying a car, enrolling the kids in school. Be as detailed and realistic as possible.
-You mentioned your kids. Research schools in the area and provide screenshots of your research. Maybe get in contact with schools in the area you want to live about registration.
Keep in mind, I'm going through this process myself, I haven't been approved at all. This is all just based off things I've seen doing my own research in other threads, and what we intend to put in our application. Hope that helps with some ideas!