The datatiddler tools we're given only go one level deep. So to encode more than one thing per index you'd need to perhaps pack everything into a string with a designated separator, and then unpack it later as needed.
But in reality, if you find that you're needing to put lots of stuff into a data tiddler, it might be better to consider using tiddlers, which are the real data units of TiddlyWiki. All the widgets and filters are based on tiddlers, with few based on data tiddlers.