I haven't been able to attach William Eccles and his family to the ones I have. (There don't really seem to have been any other Eccles but yours in Ballantrae. It is possible William is related in some way.)
The Banns for William Eccles and Janet Millar, Ballantrae, are dated 25th September 1838. The 1841 Census shows Janet Eccles, 20, at Shellknoll, Ballantrae, described as "husband fisher absent". She has two children aged Mary, 1, and James, 8 months. A search through the baptism pre-1855 shows Mary had a middle name of Taylor and they had another son John Millar Eccles baptised Dec 1842.
This post says William died in 1844: http://boards.ancestry.com/surnames.eccles/22.214.171.124.3.1/m...
In the 1851 Census they turn up at Main Street (Girvan Rd), Ballantrae. Janet appears to have married James Rae, shoemaker and there are three Rae daughters aged 1 to 5 years as well as the three Eccles.
Let me know if you ever manage to connect them up!