It's looking like there are two Nicholas Kinnishes heading up families after all. Two Lonan marriages from the Notebook;
20 Jan 1765 KINNISH Nicholas & KELLY Joney Witn: John Kneacle & Thos Quark, both lic
10 Sep 1771 KIINISH Nicholas & QUARK Mary Witn: Thos Quark & John Kermod, both lic

And these baptisms, also from the Notebook:
16 Feb 1763 Nicholas s/o Nichs KINNISH & Christian QUAYLE, illeg
25 Jan 1771 Mary d/o Nichs KINNISH
9 Feb 1772 Ellinor d/o Nichs KINNISH
3 Oct 1773 John s/o Nicholas KINNISH
9 Oct 1774 William s/o Nichs KINNISH [perhaps the burial 31 May 1784 s/o Nichls]
25 Jan 1776 Ellinor d/o Nicholas KINNISH
20 Oct 1776 Isabel d/o Nich KINNISH
10 Apr 1778 Thos s/o Nicholas KINNISH
21 Feb 1779 John s/o Nicholas KINNISH
3 Jan 1781 Ann d/o Nicholas KINNISH
16 Jun 1781 Joney d/o Nicholas KINNISH, twins, laxey
16 Jun 1781 Margaret d/o Nicholas KINNISH, twins
8 Feb 1784 Joney d/o Nicholas KINNISH
11 Jul 1784 Margaret d/o Nicholas KINNISH
3 Sep 1786 Mary d/o Nicholas KINNISH
15 Mar 1789 William s/o Nicholas KINNISH
8 Jul 1792 Elinor d/o Nicholas KINNISH
[list ends at 1793]

The illegitimate one at the top probably belongs to the first Nicholas, and it's interesting that the rest don't begin until after the second marriage. Still, there are a lot of them very close together to be from one Nicholas.

There's a Lonan burial for a Nicholas KINNISH 25 Feb 1784 including a will and a later one 20 Aug 1816 that doesn't have a will. There's 2 or 3 from Maughold as well.