You may have this information by now but... Both Joseph and Louisa Hart are listed in the Sedro Woolley Union Cemetery.
11-13-02 Hart, Joseph b. 1852d. 1933 11-13-02 Hart, Louisa b.22 Feb 1863d. 6 April 1948 d/o Niles P. & Martha (Martin) Anderson, w/o Joseph b. Sweden There is also an Emma Florence Hart listed: 11-39-09 b. Jan 30, 1890 d. 19 April 1954 d/o Joseph and Louise* (Amelson*) Hart. "SISTER" And a Dora B Young listed 10-11-36 Young, Dora B b. 10 Aug 1896 d. 13 Mar 1970 d/o Joseph & Laura* (Anderson) Hart, w/o Walter.
I've added the *s to indicate that these names are listed as these spellings and it was not my poor typing skills. I'll leave it to you to decide if they are the people you are researching or not.
Someone recently did me the favor of providing me with some bits of new information from across the country.I can only hope to pass on the same kindness.