We're getting close to midway through our first pregnancy and starting to think about names. Yup, minefield territory. We do not know the sex of baby and don't intend to find out till the birth.
DH is very keen on using the name of his Dad as a first name if we have a boy. I really get the sentiment (his father died when he was a young adult) though it isn't a name I'd have choosen otherwise (sigh). It begins with M.
My favourite boys name also begins with an M. I've ruled out using it as a middle name as our surname begins with R (MMR). Many of my other favourite names for boys begin with R (which is an alliterative pain with our surname). Anyway, I'd now like to use one of these names with my FILs name.
So a son would be: M. R. R
When he grows up and uses his name with a title (say on bank cards etc) he would be Mr M. R. R and even if he doesn't use his middle name, he's stuck with MR.
So, does this fall into the category of possibly annoying, but not a major problem or do you we shouldn't do it?
I think it'd only fall into the category of cruel if we gave him a second middle name beginning with S:
M. R. S. R_ 
I'd kind of like to use one of the R names, because I don't think I'd be keen to use them as potential first names for future boys in terms of alliteration being a bit too cute/silly.
I suppose we could use two middle names to split up the M and R. But I haven't thought of one for that and wonder if it would be too long a name..
I'm overthinking this, right? 
A girl would be so much easier, there are loads more names we both like.