The 1900 US Census has Charles F. Erickson 38yrs old born in Sweden, and his wife Kathryn H. 35yrs, old, born in Rhode Island. There are two stepsons, Homer B. Wright, 13y, born Iowa and Ralph A. Wright, 10y born in Wyoming.
The sisters that you asked about, Louise Erickson is 18 yrs old and Pearl Erickson is 16yrs old. Both were born in Nebraska, as you indicated.