Reference: http://www.ibnhomaid.af.org.sa/ar/content/هل-تُقضى-السنة-الراتبة-البعدية-لصلاة-المغرب-في-وقت-آخر
Question: If we have not prayed the recommended Sunnah units of the Maghrib prayer [for example], are we allowed to pray them at another time?
Response: Yes, the scholars are of the opinion that the recommended Sunnah units of the prayer can be made up [at another time]; there is no harm in making them up [later] in shaa.-Allaah.
