We corresponded about six months ago on this family, and I'm sorry to say I don't have anything new to report.
I looked in the MA birth index for the 1894 time frame and I don't see the John and Joseph you mentioned in the index.They may have been listed with a spelling other than Seaver/Sever.
For everyone's benefit, here is the data I did find:
The only data I have for your Michael Seaver family is from the 1900 census soundex, which finds the family in Kingston, Plymouth County MA (LDS Microfilm 1,244,863, S160-S200):
Michael Seaver, age 35, born Oct 1864 in Germany. Magdalena Seaver, wife, age 30, born Sep 1869 in Germany. Mateus Seaver, age 11, born Mar 1889 in Germany Annie Seaver, age 9, born Feb 1891 in Germany, John Seaver, age 5, born Dec 1894 in MA Alice Seaver, age 3, born Mar 1897 in MA Tilly Seaver, age 1, born Apr 1899 in MA.