Lots of people are worried about Policy Violations, and generally just about just doing things wrong when fixing orphans. Amazon has lots of information about adding to variation families, what counts as a proper variation, and what doesn't. There's a whole list of hypothetical don'ts. But I haven't found a good list of actual examples of what is and isn't a good match when looking for the proper Parent Listing for an Orphaned Child listing. 

When I first started fixing orphaned listings I did it through cases. I would look for a good parent and open a case asking seller support to fix it for me. I did this for at least six months before they changed their policy and I had to learn how to actually fix them myself. 

During that six months, I was basically trained by seller support and the catalog team on how to find the proper Parent listing for Orphans. What I mean is if they wouldn't fix it for me, they gave me a reason- the pictures don't match, different model numbers, different titles, duplicate listings...

I wouldn't recommend trying to do that for training now because they flat-out refuse to help. They "don't create variations for sellers" anymore. They want us to do it. 

But thanks to them I know what to look for, I know what details are a disqualifier and how specific we need to be when fixing orphans. I know what details look like disqualifiers but might just be a gap in listing creation. There are plenty of listings that have bad information in them or are missing information and it makes them look like they don't belong with the parent. I can show you what to look for and what to update to make things match when it is a correct match but doesn't look like it yet.