May I ask...have you tried buying a birth certificate from the Irish Civil records site? I had a quick look and there are 8 Frances Andrews listed as being born in Ireland between 1870 and 1890. If you know old Frances was when she married, or died, we could probably narrow that list down a little further. If you are confident that it was Dublin, there was only 1:
Birth of FRANCES ANDREWS in 1874
|Group Registration ID
|SR District/Reg Area
|Mother's Birth Surname
The other births registered were:
2 in Belfast. 2 in Newry, and 1 each in Dundalk, Cellbridge, Limavadt.
You can order the birth certificate from here: