By the way I do have some info on Gallahers, it is not organized at all and it's been several months since I looked at it. Can you give me birth dates or parents of Joan Gallaher?
Page 1 of that history I have a Joan Gallaher (1843 - 1896), wed William Craig of Liberty IL on 12 September 1860. Says she is buried in Pleasant View cemetery Liberty IL.
If that isn't her it might still be a place to look for your Hasting/Gallaher pair.
There was also Mary Elizabeth Hastings (1885 - 1972) wed Orsen Gallaher (1878 - 1952) on 27 December 1903.