Searching at www.familysearch.org
I found this, which appears to be Dan's deathhttps://familysearch.org/ark:/61903/1:1:FDX4-MPV
This tells how to order a death certificate from Minnesotahttp://www.health.state.mn.us/divs/chs/osr/death.html
Your Tousha might have been Thyrza
DULUTH NEWS TRIBUNE FEB. 5, 1916
CARPENTER- Thyrza Seopa was a caller at Nass Sunday. Thyrza was sick this week.
DULUTH NEWS TRIBUNE SEPTEMBER 29, 1915
Nels Josnson was cutting Oats for Aleck Cossick and Dan Seopa last week.
Miss Anna Seopa and Miss Sophia Seopa were visitors at the Hayden home Sunday.
Mrs. Dan Seopa and daughter were callers at the James Hayden home on Saturday.
DULUTH NEWS TRIBUNE APRIL 21, 1920
MARRIED IN HIBBING
Hibbing, Apr. 20
Carl Allison, Hibbing and Anna Seopa, Chisholm, were married in Christ Memorial Church.
You can search the Minnesota marriage index here, and order records if you wish.
Thyrza married John Kucher and Eva married Elmer Oikari. There is also a marriage for a Violet S.- Sophia perhaps?https://www.moms.mn.gov/Search?S=1
Unfortunately, my source for the Duluth newspaper doesn't go late enough for obits for Dan and Celia.