The only girls name my husband likes is [name]Lillian[/name]. Which is fine with me, I think it’s a beautiful name. The problem is our top boy name is [name]William[/name]. We are definitely planning on having at least 4 kids so maybe the similarity won’t be as obvious with some other names mixed in there. Are [name]Lillian[/name] and [name]William[/name] too similar for siblings? If They go by [name]Lily[/name] and [name]Will[/name] does that make it ok?
Would love to hear your thoughts 
I think it’s okay, they’re both heavy on the L’s but being different genders and different feels I think makes it okay. And they both have several nickname options if you really felt the need to separate them
I like [name]Lily[/name] and [name]Will[/name]… I’d probably use [name]Lily[/name] as a little girl’s first name, rather than [name]Lillian[/name]. [name]Lily[/name] and [name]William[/name] don’t sound too similar. Good luck!
I actually have an aunt and uncle named [name]Lillian[/name] and [name]William[/name]! I never thought the two names were too close - [name]William[/name] goes by [name]Will[/name].
I don’t think it’s too much at all. Yes, the both have lots of L’s, but they’re different enough that it doesn’t sound wrong.
Unrelated note: My niece’s name is [name]Lillian[/name] (my suggestion) and if we had a boy [name]William[/name]/[name]Will[/name] was one of the very few names that made my potentials list. You have excellent taste! 
I actually really like the names [name]William[/name] and [name]Lillian[/name] together. There is enough difference so they don’t sound the same but they’re close enough to flow nicely when you say them. Also if they are going be called by their nicknames then I definitely don’t see any problem with the name combo.
[name]Lillian[/name] and [name]William[/name] nn [name]Lily[/name] and [name]Will[/name] would be a fantastic sibset! While both names are three syllables and have a lot of l’s , the sounds are different enough so it won’t be too similar. Plus, if you’re going to refer to them as [name]Lily[/name] and [name]Will[/name], it’s not an issue at all.
Ehhh I think the full names are too similar. I would prefer to see something like [name]Lila[/name] & [name]William[/name] or [name]Lilia[/name] and [name]William[/name] or simply [name]Lily[/name] & [name]William[/name].