Another place to try is New Cathedral Cemetery. It is another diocesan cemtery out at 2nd and Butler that opened in the 1860's. You may find that even though your ancestors lived in one area, they may be buried further afield from there or from one another. I have seen that in my family, where members pre-deceased spouses by 30+ years and circumstances (like the 1918 influenza, the depression, etc.) led to people being buried wherever they could physically put them or afford to put them.

Good luck