Hi Rose, I would do a search on ScotlandsPeople on the 1901 census. If you haven't used it before, it costs, but it well worth it as you can do it from the comfort of your own home, download images of the censuses etc. Put in a rough range of ages, if you know they were born around 1870. For example, aged 20-35. You could also try the 1891 and 1881 censuses in case they came over earlier. The women may have been married by then so you may have to search marriage certificates and then look under the married name on the census.
You could also try and search for their death certificates and find a location from those (and lots more). Women are recorded under their maiden and married names so you can search on the maiden name.
I would try under various spellings of the name eg Kerwin, Kirwin etc. Things are often mis-spelt of mistranscribed if the writing is unclear. Persevere.
Can you list their dobs and the parents' names and rough dobs in case I come up with something.
Good luck
Lesley
PS Mine also came over from Ireland to Scotland in c1860s so I am used to searching things like this.
