Husband and I decided on the first name for our little one, but we are having a hard time with the middle name! We want the middle name to possibly take after someone in the family or be my maiden name, then realized all the great-grandmothers’ & grandmother’s names and my maiden name starts with a “J”. So we thought of her middle name just being “J.” to represent the grandmothers and my maiden name. [name_f]Adeline[/name_f] J. Last
Thoughts?
I think I’d prefer it written out phonetically: [name_u]Jay[/name_u], or even [name_u]Jae[/name_u], if you prefer. I know it has been done before (Harry S [name_m]Truman[/name_m] and [name_m]Ulysses[/name_m] S [name_m]Grant[/name_m] being famous examples), but to me having just an initial is a bit odd, and could cause some administrative headaches. I really do like the symbolism of the J for you – all those coincidences! – but would definitely prefer it in a “full” form.
I agree with @katinka. [name_f]Adeline[/name_f] [name_u]Jae[/name_u] is adorable!
I think it’s a really cool idea. I do think that maybe spelling it out to [name_u]Jay[/name_u] or [name_u]Jae[/name_u] might make her life a little easier in the long run, but I’m not sure how difficult having just J would be since a lot of times middle names are shortened to their initial anyway. Regardless of what you choose to do, I think [name_f]Adeline[/name_f] J is a really cute name.
I do think [name_u]Jae[/name_u] or [name_u]Jay[/name_u] would be more wearable but J works too 
This is something we do in my family and I will definitely use it for at least one of our kids. I love just using the letter J. I think I would prefer it without the period though (Adeline J Last). She will be asked what the J stands for on legal documents and such, but it’s not a big deal and is unique but not outlandish.
I don’t recommend using the single letter, J. I can only imagine how many conversations will be had over her lifespan “not [name_u]Jay[/name_u], just the letter J”. Also, from the family history of females with J middle names, you have many choices of a J name to give to her, or choosing another name that has yet to have been used but still carries the J tradition.
I like this idea! In the scheme of different spellings and whatnot I don’t think it would be all that annoying to have to specify “just the letter J”, although I don’t have experience with this myself. I agree with PPs that it seems unusual but not outlandish. I like that it honours all of the J-named people in your families equally.
The other thing you might consider doing is picking a totally new-to-your-families J name for the middle name.
I like the simplicity of J, but I wouldn’t add the period.
[name_u]Jae[/name_u] for sure
I really don’t like just the letter, and to be straightforward I think many (most?) people will see it as comically weird. Your child may not appreciate explaining it, either. I’d go with [name_u]Jae[/name_u] or [name_u]Jay[/name_u] like others have suggested if you’re set on using the letter.
I agree with [name_u]Jae[/name_u] personally!
I think it would be better is J was spelt out like [name_u]Jae[/name_u] or [name_u]Jay[/name_u]. It would make her life a little easier when filling out paperwork. As well as when someone says what you middle name and she says J. It feels like she should spell it out
I think that [name_u]Jae[/name_u] or [name_u]Jay[/name_u] would be better than just the letter. Another idea would be to use a name that starts with the syllable “jay” because it emphasizes what you’re trying to honor without being too close to any single name (of course my suggestions might not be quite right for that since I don’t know all the names involved)
[name_u]Jaylin[/name_u] / [name_f]Jaelynn[/name_f] (my favorite)
[name_u]Jade[/name_u] / [name_f]Jayde[/name_f]
[name_f]Jane[/name_f] / [name_f]Jayne[/name_f]
[name_f]Jada[/name_f] / [name_f]Jayda[/name_f]
etc.
I agree with others that using Jay/Jae would be somehow simpler. The period after the letter implies that the letter stands for something so that would cause me some confusion as well.
[name_m]Just[/name_m] some things to think about.
I love the symbolism with just the J…. But I feel realistically speaking by I wouldn’t do it. I feel it would be a lifetime of headaches and standing out from the crowd. I would maybe do [name_u]Jae[/name_u] or just do a name that starts with a J so she can represent and honor but also make a J name for herself if you get what I’m saying.
[name_f]Lovely[/name_f] name, I’d probably spell out J as [name_u]Jay[/name_u] or [name_u]Jae[/name_u]. I don’t know if I would want my middle name to just be a single letter.
I love the idea, but to make her life easier I’d go with [name_u]Jay[/name_u] or [name_u]Jae[/name_u]. The connection with J is still there but it’ll be easier. I like [name_u]Jay[/name_u]!
I like using just the letter !
Agree no period. Does just a single letter work legally where you live? I don’t think its an option in the US. Otherwise I don’t see any issue with it.