With today’s print technology it would not be hard at all to tamper with newspaper copy.
However, in 1961, printers were still using hot type and linotype machines. They would have had to bribe a linotype operator to insert the material — not something a novice could do. I suppose that would be a possibility, but it seems unlikely.
Considering what we know of Hawaii’s lax record-keeping, it would have been much easier just to record the birth with the proper authorities, tell them whatever manufactured tale you wanted them to know, and make it part of the official record.
There’s an area of research that needs attention, the activities of the organisation Frank Marshall Davis belonged to; The Protection of the Foreign Born. We need to know the activities they engaged in, we understand their objectives, but how did they achieve them?
Did they provide false indentification, did they fabricate documents for marriages, births and deaths for example?