Best form (or least harmful from libertarian perspective) of welfare subsidy that I know is The Life Account. People can withdraw money from there whenever they need (no need to ask any permissions), so it's almost like a basic income. But it's way more better than basic income because it's personal.
If needed, the account can go negative, but voluntary deposits are encouraged with incentives for saving. If an individual doesn't need any welfare benefits at the moment, he doesn't need to withdraw any, unlike what happens with basic income.
I don't know how much it has been discussed globally, but a few years ago Finnish thinktank Libera published a report: The Life Account – Reforming the Nordic Social Security Model to Encourage Work, Employment and Saving (pdf).
You can skip first few chapters and start reading from page 31 (The Life Account).