I think it’s a lost cause, unless you go for [name_u]Indigo[/name_u] (I sort of love that name). I’m not a fan of forcing one parent to use a name they hate if a compromise can be found, instead. From your signature, it looks like you’re not shy of using unusual names. I think [name_u]Indigo[/name_u] would fit in very neatly with your other boys’ names. On the other hand, [name_m]Ignatius[/name_m] could make a pretty stunning middle name if you can find the right first for it. Then Dad could still call him [name_m]Iggy[/name_m] - on occasion.
Here are a few suggestions that [name_m]Ignatius[/name_m] might go with (because I can’t think of any other [name_m]Iggy[/name_m] first names, either):
[name_m]Hyrum[/name_m] [name_m]Ignatius[/name_m]
[name_m]Raines[/name_m] [name_m]Ignatius[/name_m]
Gresham [name_m]Ignatius[/name_m]
Rigdon [name_m]Ignatius[/name_m]
[name_m]Miles[/name_m] [name_m]Ignatius[/name_m]
[name_m]Milo[/name_m] [name_m]Ignatius[/name_m]
[name_m]Alisdair[/name_m] [name_m]Ignatius[/name_m]
Revere [name_m]Ignatius[/name_m]
[name_m]Stellan[/name_m] [name_m]Ignatius[/name_m]
[name_u]Tristan[/name_u] [name_m]Ignatius[/name_m]
[name_m]Fisher[/name_m] [name_m]Ignatius[/name_m]
[name_m]Fletcher[/name_m] [name_m]Ignatius[/name_m]
[name_m]Theodore[/name_m] [name_m]Ignatius[/name_m]
I also think you have some names in your signature that could go pretty well with [name_u]Indigo[/name_u]:
[name_u]Indigo[/name_u] [name_u]Tobin[/name_u] / [name_u]Tobin[/name_u] [name_u]Indigo[/name_u]
[name_u]Indigo[/name_u] [name_m]Lorcan[/name_m] / [name_m]Lorcan[/name_m] [name_u]Indigo[/name_u]
[name_u]Indigo[/name_u] [name_m]Cadmus[/name_m] / [name_m]Cadmus[/name_m] [name_u]Indigo[/name_u]
[name_u]Florian[/name_u] [name_u]Indigo[/name_u] / [name_u]Indigo[/name_u] [name_u]Florian[/name_u]
[name_m]Casimir[/name_m] [name_u]Indigo[/name_u] / [name_u]Indigo[/name_u] [name_m]Casimir[/name_m]
[name_m]Calvin[/name_m] [name_u]Indigo[/name_u] / [name_u]Indigo[/name_u] [name_m]Calvin[/name_m]
Putting [name_u]Indigo[/name_u] in the first spot might make it sound like an adjective instead of a name, though most people won’t hear the first and middle together. [name_m]Casimir[/name_m] [name_u]Indigo[/name_u] and [name_m]Theodore[/name_m] [name_m]Ignatius[/name_m] might be my two favorite suggestions for you. [name_m]Lysander[/name_m], [name_u]Elliot[/name_u] & [name_m]Casimir[/name_m]; [name_m]Lysander[/name_m], [name_u]Elliot[/name_u], and [name_u]Theo[/name_u]. I might like [name_u]Tobin[/name_u] [name_u]Indigo[/name_u] better than [name_m]Theodore[/name_m] [name_m]Ignatius[/name_m], though, and I also like [name_m]Lysander[/name_m], [name_u]Elliot[/name_u], and Rigdon. Oh, maybe that’s another [name_m]Iggy[/name_m] name! Then you could dispense entirely with [name_m]Ignatius[/name_m]. And Rigdon sounds pretty good with several of your signature names:
Rigdon [name_m]Apollo[/name_m]
Rigdon [name_m]Cadmus[/name_m]
Rigdon [name_m]Casimir[/name_m]
I like the sibset of [name_m]Lysander[/name_m], [name_u]Elliot[/name_u], and Rigdon. Each name has a unique vibe to it, yet they seem to hang together pretty well. I like Rigdon [name_m]Apollo[/name_m] best of those three, to not repeat the Ca- or even [name_m]Cas[/name_m]- from [name_u]Elliot[/name_u]'s middle.
Good luck!