Danylovych is a patronymic. We prefer not to use them as LNAB for medieval aristo profiles, though it should definitely be in one of the first/middle name fields, using one spelling or another.
He's a Rurikid. There's no concensus on a LNAB for those, and it will be hard to have one, between those who prefer Anglicized names, those who prefer the original Cyrillic characters, and then should we prefer Rurikovich/Rurikovna depending on gender, or the dynasty name Rurikovichi for everyone. Plus this is a "Ukrainian" branch and they have slightly different letters/spelling. Рю́риковичи seemed to get most support. It's a real can of worms, anyway.