What is the term when fixing one issue positively impacts other issues?

An example of what I am trying to ask is - The head of household for a family is undocumented, earning a little under minimum wage and renting a room. However, if he is able to get his green card he will be able to earn more than minimum wage allowing him to be able to afford his own apartment. Getting his own apartment will then lead to his children staying in school, etc.

There are several colloquial expressions for that phenomena...

A snowball effect:

a situation in which something increases in size or importance at a faster and faster rate (From Cambridge online dictionary)

A domino effect:

a cumulative effect produced when one event initiates a succession of similar events (from MWO)

A ripple effect:

a spreading, pervasive, and usually unintentional effect or influence (from MWO)

Or simply the benefits will grow. If you do a search in a thesaurus for "grow", "build" or "wax", you'll get many other synonyms for this concept.

A technical economic term for this would be "positive externality." An externality is just a side effect of a transaction or other economic decision.

So for example, suppose you give your house a fresh coat of paint. The result is that your house becomes more attractive, and maybe its sale value increases. That's the main effect. But that also means your neighbors have a nicer view, and that might increase the sale values of their houses too! That's an externality, a side-effect, and it's a positive one.

"Externality" might be too technical, though, and so "positive side effect" might be more appropriate for a general audience. However, it doesn't capture quite so precisely the idea that these add value to a decision.

I have also heard these referred to, more colloquially, as "knock-on effects." (Think of one object knocking on another unexpectedly to make sense of this.) To my ear, that's nice here because it suggests a greater degree of unexpectedness than "side effect" does. It too would need qualification though; knock-on effects can also be positive or negative.

I don't know of any single term that automatically implies a positive effect. "Side benefits" comes a bit closer though.