May I add a source to a friend's tree

I found death records for a school teacher I knew in childhood who died in 1987. I noticed on FamilySearch that ordinances were done for him with the exception of sealings to parents and spouse because additional information is needed. The death records document his spouse's name and parents' names and give dates. His son was the informant, and I believe he died a few years ago. I realize I myself cannot request these ordinances as I am not related to him, but entering the pertinent information into FamilySearch will likely allow the remaining ordinances to be completed by one of his relatives. Am I permitted to attach these death records to his name, even though I am not a relative?