Sorry! I have confused two branches of my Brown ancestors.
Thomas Browne born 1789 to Thomas Browne and Margaret Henning in Rathfriland?
Married Elizabeth Arnold born Rathfriland 1809. I do not know where they married, but think Rathfriland might be a start.
Parents of Jane Browne, who married Samuel Beggs Brown, born Belfast 1840 son of Isabella Beggs and John Brown, who married in 1839, but I do not know where.
I don't have much information about Beggs or Brown, except that The parents of Isabella Beggs were Samuel Beggs and Sarah Mitchell and the parents of John Brown were John Brown (Killyleagh) and ? Wilson
Thank you for pointing me towards the Presbyterian church records at PRONI.