Nothing needs to be done. But you might be able to publish it showing a few ultrasound pictures before and some photos after the birth ! At least post them on RESEARCHGATE as a project you are part of.
It is difficult answering this question because it lacks information. What is the gestation? At what gestation was the othe other fetuses found not to be viable. What is the chorionicity, etc
An informed opinion can better be made with further information.
If you observe 2 fetuses papyraceus it means that intrauterine death of them was in early gestation, so the prognosis for alive fetus will be favorable. The only thing you have to screen for cervical shortening to prevent preterm birth.