Please contact me via e-mail. I do have some info on Kate, and I think Wallace is buried in Springfield also. Have you visited that cemetery? I think I have pictures of the stones. I think Wm. Wallace's will may be available at Jefferson County Courthouse near Denver. He may have died in Denver. I think I have a copy of a description of Kate's wedding and her house is still standing. I think she converted the house into a benevolent society or something. I may have a picture of the house.
I think the Halberts were somehow connected to Abe Lincoln's wife, but I may have some families mixed up. I have seen a mention of the Fondeys of Spring field (using the name Fonda) and their social association with a writer (Browning maybe?)
Fondey is in 1850 Census listed right next to Lincoln.