Go to Rootsweb's WorldConnect site -- http://wc.rootsweb.ancestry.com/cgi-bin/igm.cgihttp://wc.rootsweb.ancestry.com/cgi-bin/igm.cgi -- someone else is working on this couple. They don't have full date of death for Silas. I'm assuming you have that because you've seen his DC. You might want to share that. Comparing notes and clues sometimes pays off for both parties.
They have posted more info on Mary and her family, that might help you, also.