As Brian states there is no guarantee that any of the four made wills.
They do not appear in the 1841 census for Patrick (there is a John aged 78 in Peel) and would probably all have been at least 70, if still alive. They became parents in the 1790s, so you can probably narrow down the period of death to between 1800-1841.
In wills you have (from Brian's index) these possibilities:
Margaret Peel 1827 0106245 (burial not found)
Margaret Patrick 1841 0106249 (doubtful - probably Margaret Moore buried Patrick age 62 Feb. 9 1841)
Thomas Patrick 1810 0106237 (Probably Patrick Moore buried Patrick Jan. 29 1810)
Ann German 1832 0106432 (Possibly Ann Moore buried Patrick March 12 1832)

Another thing to check is Monumental Inscriptions.