We cannot have a welfare state and open borders, birthright citizenship, etc. All the myriad ways of gaming a system are guaranteed (and given the human condition is eternal, no hope of good behavior, nor a lack of unintended consequences).
So the best answer that works is returning to the founders’ model. No welfare in any form from any form of government further removed than a neighborhood. All citizens responsible for themselves, their actions and the consequences. Where charity is needed, it’s not the government’s job, but civil society, starting with the family and moving on up. All (necessarily) voluntary. There will be tragedy. But guaranteed less than today (esp. when we think globally and reflect on the 100s of millions of lives ended early in the pursuit of communism’s perfect man, to say nothing of the billions of lives lived to absolutely no betterment of mankind.. where the outputs of their factories where often worth LESS than the inputs.. no better, likely worse than slavery since many of the participants were held in ignorance of their state).
Then we would not have any reason to be concerned about the borders. Since the only asset of any long-term value is applied human intellect, integrated over time, we’d be and remain the wealthiest nation on earth. And maybe, just maybe, those who end a baby-in-the-womb’s life early will be seen as what they are, destroyers of the only true value.