In German, we don't have a single word, but we can say Verwaiste Eltern. (lit. orphaned parents)
Note: Somebody who lost their parents is called Waise.
I think in English we are left to use two words as well, just as in German.
The English word ‘
orphan’ comes from the Greek
ὀρφανός meaning
bereft (of a father, or of parents), fatherless, desolate.
For searching on it, there does seem to be a term ‘
orphaned parents’ in this context, used by the British news paper
The Telegraph:
http://www.telegraph.co.uk/news/wor...edy-of-Chinas-orphaned-one-child-parents.html
The Indian news paper
The Hindu uses the term ‘
orphaned mother’, (yet in this case, it is actually used to mean
abandoned).
http://www.thehindu.com/todays-pape...n-left-to-fend-for-herself/article2215467.ece
In as much as there doesn't seem to have been any official term — neither historically, nor etymologically — such as we have with ‘widow’ / ‘widower’ or ‘orphan’, I would think a turn of phrase such as ‘
orphaned parent(s)’, ‘
orphaned mother’ or ‘
orphaned father’, (or ‘
bereaved parent(s)’, etc.), would be the only means to express the concept in English. The legal term ‘
surviving parent(s)’, etc., can be used in a Last Will & Testament, yet I can't imagine this to have much currency outside of the law, with the possible exception of an obituary.
Perhaps it is noteworthy that there are no words for a brother or a sister who has lost his or her siblings.
(A rarely used, but similar term for the surviving party in a betrothal is
‘widowed-fiancée’ or
‘widowed-fiancé’, for someone officially engaged, but whose intended spouse has died before the wedding).