Hello...
Following on from the naturalisation details supplied by Lucy...
This might be a red herring but the only Mate BRJLEVICH (BRJLEVIĆ) who gets a mention in the mid-1880's Metković birth registers happens to be a father of twins.
Here are images of the Register entries...
Entry no.60
BRJLEVIC,Ivan_1884birth.jpghttp://www.rootschat.com/links/0yhs/Entry no.61
BRJLEVIC,Jela_1884birth.jpghttp://www.rootschat.com/links/0yhr/You can download the images to your computer by clicking on the "Download" button. You can then zoom in and read the entries a lot easier.
Here's a rough translation...
Born: 28 Prosinac (December) 1884
Baptised: 1 Siječanj (January) 1885
Child's name: Ivan BRJLEVIĆ
Child's name: Jela BRJLEVIĆ
Zakonit/Zakonita (Legitimate)
Mother: Mara MARINOVIĆ
Father: Mate BRJLEVIĆ
Both parents reside in Metković
Parents were married on 25 Veljača (February) 1884
Married in the Roman Catholic Church
Godparents: Stipan VUICA and Stana RADIĆ
Witness: Pero VUKSA
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Croatia, Church Books, 1516-1949https://familysearch.org/search/collection/2040054-----
If you want to take this further I think you need to go backwards.
Here's the 1884 marriage of Mate BRJLEVIĆ and Mara MARINOVIĆ as a starting point.
BRJLEVIĆ_MARINOVIĆ_1884marriage.jpghttp://www.rootschat.com/links/0yht/-----
My thinking is that as Momic/Momici (mentioned earlier by Lucy) is just a few miles from Metković this Mate and Mara BRJLEVIĆ are somewhere in the picture. Unfortunately they can't be the parents of Ante BRJLEVIĆ as he was born only four months after the twins. Possibly aunt and uncle?
I've looked through the Metković birth registers up to 1890 and there is no other mention of the name BRJLEVIĆ which implies that, at least in this area, BRJLEVIĆ is not that common a name.
There's no mention in the Metković birth registers of the Momici births of Ante b.1885 and Filip b.1888. Or at least none that I can find. Possibly Momici came under a different parish, although that seems unlikely as it wouldn't be more than a ten minute donkey ride away from Metković. Family Search has some other Croatian Birth Registers labelled
"Vid (Metković)" which I had a quick look through but nothing jumped out.
As I said earlier, may well be a red herring but worth looking at further.
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Came across the following a few days ago. Is it related to this family...
https://familysearch.org/pal:/MM9.3.1/TH-1961-39403-2067-93Regards
Beg