Don't know if this will be of any help to you re Nivens but in Coylton Churchyard there are two monumental inscriptions to the family.
'Er by James P Niven Esq merchant Singapore in affectionate remembrance of his wife Catherine McLimont Pringle d at Singapore 23 Mar 1867 aged 38 yr 8mths; also of his daus Annie Aitken d Hillhead Coylton 19 Nov 1872 aged 14 yr 6mth; Jessie Campbell d Singapore 9Jan 1874 aged 20yr 6mths; the above James Parker Niven d at Hillhead 6 Sep 1876 aged 56; also his son Lawrence d Hong Kong 31 May 1890 aged 33; also his daus Agnes Alice Hamilton( Mrs Alec Buyers) d Shanghai 29 Jun 1919 in her 64th year; and Jeanie Buyers (Mrs Sam Groundwater)'
'In memory of Laurence Niven late of Singapore d Hillhead 21 Aug 1876 aged 51.' 'Also in memory of his wife Jane Newbold d Singapore 21 Jan 1906 aged 69 and is interred there.'
Hope this helps
Cat30