I think it’s fine. [name_f]Lucy[/name_f] is such a classic, well-used and familiar name and it has a different feel to playful, nickname-y [name_f]Lou[/name_f]. Maybe if you were going with ‘Lu’ or [name_f]Lou[/name_f] itself it might feel wrong; equally, if your coworker’s daughter was called something like [name_f]Nyx[/name_f] and you went with [name_f]Nixie[/name_f], or if she was called [name_f]Opal[/name_f] and you went with [name_f]Opaline[/name_f], it might feel a bit like stepping on toes, but in this case, it doesn’t feel like that at all