I think it reaaally depends on the name!
For me, the nickname argument is meaningless. Sure, [name_f]Elizabeth[/name_f] ‘Lizzie’ and [name_f]Eleanor[/name_f] ‘Ellie’ sounds fine in theory, but how do you know that [name_f]Elizabeth[/name_f] won’t want to go by [name_f]Elle[/name_f] or [name_f]Ellie[/name_f] when she’s older, or that her friends/classmates won’t nickname her [name_f]Ellie[/name_f] anyway? You can’t guarantee either of those.
In your [name_f]Elizabeth[/name_f] / [name_f]Eleanor[/name_f] / [name_f]Felicity[/name_f] / [name_f]Genevieve[/name_f] example, my only issue is [name_f]Elizabeth[/name_f] & [name_f]Eleanor[/name_f]. I don’t think the “el” of [name_f]Felicity[/name_f] is nearly as obvious, I probably wouldn’t notice it, and they don’t share any nicknames. [name_f]Elizabeth[/name_f], [name_f]Felicity[/name_f], [name_f]Stella[/name_f] and [name_f]Genevieve[/name_f]? 100% fine. [name_f]Elizabeth[/name_f], [name_f]Eleanor[/name_f], [name_f]Stella[/name_f] and [name_f]Genevieve[/name_f]? I wouldn’t do it.