The fact that they are all from the former GDR made me wonder if the name could be connected to Russia somehow. But alas... in Russian, силона (silona) is only the genitive of силон (silon), which is the name of a type of polymer fibre that was developed in the 1940s by the Czech chemist Otto Wichterle (1913-1998) and others:- https://ru.wiktionary.org/wiki/силон (in Russian) - https://en.wikipedia.org/wiki/Silon (in English)I strongly doubt that East German parents would want to name their daughter after something like that! In their case it is probably more likely that Silona is a combination of two existing names, such as Silke with Ilona or even Aliona.
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