I know the DOB and country and year of marriage
What about "... Someones death date ..."?
If you do not know the "Death" details (ie. 'Date' and 'Place'); then, leave it "as is".
If an individual/person is OVER 110 Years of age; then, the "Death" details can usually just be left as "Deceased" (ie. with NO 'Date' and 'Place').
Whereas, if an individual/person is 110 Years of age or LESS; and, you CANNOT substantiate a (ie. provide "Evidential" Proof of) "Death"; then, the individual/person SHOULD be left as "Living"; and, will remain in your "Private Spaces"; but, NOT be viewable to other Users/Patrons.
The latter is required for reasons of "Privacy".
When; and, if, you find evidence of "Death"; then - and ONLY then, can/should you "Change" the individual's/person's "Status" from "Living" to "Deceased".
I hope that helps.