New Post: Making sure fixes don't get lost from one release to another

We have found that we "lost" a fix from one release to another. I need help in determining the best thing to do to help make sure this doesn't happen again.

Picture the "Advanced Branch Plan" scenario. Over time we have released a major version 1 with all the servicing branches under it. Later we release another major version 2 after development is complete. Version 2 gets brought through Main and has its own servicing branches created below it. This happens again with version 3.

So...I have 3 major versions all with servicing branches beneath and each version is still getting serviced.

A fix goes into version 1. It needs to get to version 2 and then version 3.

The only way I see to get that change where it needs to go is to RI it all the way to Main, then cherry-pick it down into the servicing branches for version 2. I have to cherry-pick because version 3 has already moved through Main and I don't want to pick up any of that new development.

Question: how can I make sure that all fixes that have been serviced in version 1 after version 3 was released have been Reverse Integrated and then cherry-picked down to subsequent versions?

Is this a good way to do it? Is there a better solution?

Thank you!