My sister takes extended release morphine , can she take a suboxone 24 hrs after her last dose?

Not safely: If she has been prescribed suboxone, it is the responsibility of the prescribing physician to make sure her "induction" is done safely - at least 2-3 days after long-acting opiates and being in withdrawal. If not, it may precipitate a very severe withdrawal reaction, with violent nausea/vomiting, diarrhea, terrible pain and even delirium. If not prescribed, definitely no! do it with supervision.