how can we get central americans to stay in central america?

Stop inviting them in and secure the border.

ALLOW socialism, communism, consumerism, voyeurism, sadism, taoism, maoism, starvation, libation, master... oh, well, you get the point. Just let them do THEIR thing. Don't try to POLICE the world. Vietnam is VERY NICE, totally under communism. So is CHINA.

Another way is to issue BIOMETRIC social security cards. Photo...thumbprint... no card, no job; alien stay home! No job:(

Give them a reason to stay where they're at. If you're leaving your country there's got to be a reason that you're leaving get rid of the reason that you're leaving the country and the people will stay

Easy: stop destroying their countries through sanctions, embargoes, coups, invasion, and other forms of political and economic intervention and warfare. And, end American puppet regimes like the Moïse regime in Haiti so that they can run the country in their own interests.